Sheldon Cooper has a guilty pleasure. It is a secret passion of his, about which neither his best friends, nor his girlfriend, are aware. He has six files on his laptop dedicated to this guilty pleasure. Each of these files has been painstakingly protected by extensive firewalls, and 16-digit password combinations that only a person with eidetic memory like himself could possibly remember.

"I'd also like to thank my Mee-Maw, who correctly predicted that the neighborhood boys, who shoved my head in an excrement-filled toilet, when I was ten years old, would end up dead, in jail, and on a reality television show, where contestants consume cow genitalia for money, respectively," Sheldon reads out loud from his computer screen.

Sheldon smiles in self-satisfaction. Of all the variations of his Nobel Prize speech he has written over the years, this one has always been his favorite . . . so much so, in fact, that he's often considered discarding the other versions. Yet, no matter how many times he's tried, he simply can't bring himself to delete them.

"Be strong, Sheldon," he scolds himself, as he drops and drags the icon for his least favorite version of the speech to the virtual Recycle Bin, allowing the document to hover over its edge precariously.

His hands are shaking . . .

Knock, knock, knock . . .

"Sheldon," a familiar female voice echoes from the front door.

"Phew, that was a close one, Number 5. I'll chalk it up to temporary madness," Sheldon exclaims, as he returns the Word document to its properly password-protected place, and moves toward the door.

He then leans against the door frame, arms folded across his chest, waiting . . .

Knock, knock, knock . . .

"Sheldon . . . I know you're in there. I can see your Flash t-shirt through the peep hole," Penny scolds in frustration.

Sheldon pretends to innocently examine his nails. Yet, a subtle smile plays across his lips, belying his unconcerned body posture. Though he'd never publicly admit it, there are times when he enjoys teasing his blonde waitress friend almost as much as he enjoys editing his Nobel Prize speeches.

"Well, of course, I'm here, Penny," he replies calmly. "Where else would I be at 8 p.m. on a school night?"

"Open the door, Sheldon!" Penny demands.

"I have every intention of opening the door, Penny," Sheldon explains. "I'm just waiting for you to finish."

"Finish?" Penny asks in confusion.

"Yes, finish," Sheldon replies. "Knock, knock, knock, Sheldon . . . knock, knock, knock, Sheldon . . . You're not finished."

Penny rolls her eyes. "You're kidding, right?"

"I'm most certainly not kidding. Had I been kidding, I would have completed my statement using the word, Bazinga, which, as you know, I did not," Sheldon retorts.

"Fine," she grumbles.

Knock, knock, knock.

"Sheldon," she says exasperatedly.

Immediately, Sheldon opens the door with an exaggeratedly cordial grin on his face. "Is that Penny? What a pleasant surprise! Come on in, and have a seat . . . just not in my spot."

But Penny has no interest in sitting. Instead, she begins to pace back and forth angrily across Sheldon's living room, like a bull preparing to charge at a matador.

"You seem distressed, Penny. Can I interest you in a hot beverage?"

"Where's your roommate, Sheldon?" Penny asks pointedly, ignoring her friend's inquiry.

"Oh, Leonard had to work late," Sheldon explains distractedly, as he extracts two matching mugs from the kitchen cabinet.

"I see," Penny says sternly, as she removes two packets of Hot Cocoa Mix from the pantry, and pours them into the mugs Sheldon has placed on the counter, while he heads to the stove to boil the water.

Of all of Sheldon's acquaintances, Penny is the only one he will allow to help him make hot cocoa. Amy will inevitably add too much milk, or fail to properly stir the concoction, rendering the beverage much too chunky in consistency for Sheldon's taste. As for Leonard, he insists that heating the cocoa in the microwave tastes exactly the same as doing it on the stove, an idea Sheldon finds absolutely preposterous.

"And has he been doing that a lot, lately . . . working late, I mean?" Penny continues.

Sheldon pauses over the stove to ponder this question. "Now that you mention it, Leonard has worked late every Monday and Thursday night this month. Who knew reinventing the proverbial wheel of scientific discovery could be so time-consuming?" He muses.

Penny narrows her eyes, as she furiously stirs the pot before her. The steam rising from the oven appears to be coming out of her ears . . . an optical illusion that Sheldon finds fitting, given the waitress' sour mood. "And this doesn't bother you at all?" She asks bitingly, "Your roommate's sudden dedication to his work?"

"On the contrary," Sheldon corrects. "At first, it bothered me very much. As you know, Monday nights, are Thai takeout nights. Leonard's failure to partake in our ritual did abysmal things to my digestion process. But since I've informed him of this, Leonard has taken it upon himself to have Siam Palace deliver me my chicken satay at precisely 5:45 p.m. each Monday night. And now, I am happy to report that my digestion is just dandy."

"I'm so glad," Penny mutters sarcastically, as Sheldon pours hot water into her mug.

"Why thank you! I'm glad too," Sheldon responds gleefully.

"What about Amy? Where is she tonight?" Penny presses, closing her eyes briefly, as she inhales the aroma of the hot cocoa mug in front of her.

Sheldon always makes the best hot cocoa. She thinks to herself with a smile. Then, she remembers that she's supposed to be mad, and starts glaring at the wall again.

"Actually, she's working late too. She mentioned something about a Capuchin Monkey Emergency."

"Hmph, and you don't find that the least bit convenient?" Penny probes.

"Absolutely not! If you have ever seen the Planet of the Apes movies, you would know that Monkey Emergencies are not only most inconvenient, but, at times, downright apocalyptic."

Penny groans, and slams her cocoa mug down on the kitchen table. "Sheldon, Leonard and Amy are having an affair!"

"What?" Sheldon asks incredulously. "I'm sorry, Penny. But your conjecture is simply illogical. Amy's taste in men is much too impeccable for her to willingly date someone as painfully ordinary as Leonard . . . no offense."

Penny shakes her head pitiably, as she takes a mournful gulp of her cocoa. "Face the facts, Moonpie. You're being played like a fiddle."

"First of all, only my Mee-Maw can call me, Moonpie. Second of all, I've always considered myself more of a rare violin than a fiddle. Third of all, any scientist worth his salt would never accept a statement of that sort, without first receiving substantial evidence of its accuracy. So far, you've provided me with nothing but banal coincidence, and a horrifying naivety about the potential danger of monkeys."

"Fine, I'll prove it to you," Penny insists smugly. "Call Amy, right now. Actually, don't just call her, Face Time her."

"OK, I will," replies Sheldon, who is always up for a challenge.

He slips his phone from his desk and Face Times Amy. She picks up on the third ring, looking rather distracted. "Um, hi Sheldon. Is something wrong?"

"Not at all, Amy. I was just checking in on my girlfriend, engaging her in some casual chit-chat."

"That's very sweet of you, Sheldon," Amy answers uncertainly. "Unfortunately, I'm a bit busy right now."

"Yes, of course, Amy. I completely understand," Sheldon replies, casting a stern look in Penny's direction. "I'll let you go, in just a moment. But . . . refresh my memory, Amy. Where are you right now?"

Amy's brow furrows in concern. "Sheldon, please forgive me for saying this. But it was always my understanding that an eidetic memory never required refreshing."

Sheldon's eyes widen, an indication (at least in Penny's experience) that he's about to tell a lie. "Yes," he begins tentatively. "Normally, that's the case, but, I must admit I haven't been quite myself lately. Penny's been forcing me to imbibe alcohol in mass quantities. And I'm afraid it's been adversely impacting my short-term memory. She has many Svengali-like qualities, that Penny."

"Indeed," Amy agrees sympathetically. "I can certainly sympathize with the allure of my bestie's entreaties to the dark side. She can be quite the sensual siren, when she wants to be."

Penny crinkles her nose at this.

"Anyway," Amy continues. "I'm at work . . . Monkey Emergency and all."

As if on cue, a chorus of monkey cries can be heard in the background. "I'm sorry, Sheldon. I have to go. It appears the monkeys are staging a mutiny," Amy exclaims, before abruptly disconnecting the call.

Sheldon crosses his arms across his chest triumphantly. "There you have it . . . a real life Monkey Emergency. Now, don't you feel ridiculous?"

Penny says nothing. Instead, she pulls out her own phone, and dials the telephone number of the lab where Amy works. "Hi, yes . . . Amy Farrah Fowler, please . . . What . . . you say she left hours ago? Well, than I guess I'll have to try her cell phone. Thank you."

Penny shrugs her shoulders at Sheldon in a non-verbal "I told you so."

But Sheldon is still not convinced. "Clearly, the lab is protecting Amy's identity from those mutinous monkeys," Sheldon answers matter-of-factly.

Penny groans inwardly. "Come on, Sheldon, that's . . . Fine, read this text message I got from Leonard yesterday."

Sheldon peers over Penny's shoulder. Her hair smells just the slightest bit like lemon meringue pie, a scent he finds rather pleasant, and slightly intoxicating. "Downtown . . . I'm excited," he reads. "Well, shame on Leonard, that's not a grammatically correct sentence. Except, maybe if Downtown was a proper noun, like someone's name. But since he was talking to you . . ."

"That's just it, Sheldon. He wasn't talking to me. Read the message below it."

"Sorry, I sent this to the wrong person," Sheldon reads aloud. "Well, of course he did. He meant to send it to someone named 'Downtown.'"

"No, he meant to send it to, Amy," Penny insists. "You see, later that day, I found the same message on her phone. I just . . . I don't know . . . I have this feeling that downtown means DOWN-TOWN."

"Penny, hasn't anyone ever told you that, when defining a word, you should refrain from using that same word in the definition?" Sheldon chides.

"No! I mean, downtown, like a guy going downtown on a girl."

"I'm afraid I'm still not following," Sheldon admits.

"SEX, Sheldon! I'm talking about Leonard and Amy having SEX . . . with each other."

"Oh, so what you're saying is 'downtown' is euphemism for coitus," Sheldon exclaims triumphantly.

"A euphe-what-em?" Penny inquires confused. "Listen, are you going to help me, or what?"

"Well," Sheldon replies thoughtfully. "That depends on what you're planning on doing."

Penny considers this for a moment. Truth be told, she hadn't really thought this plan out too much in advance. "I want us to catch them in the act," she says finally.

"And then . . ." Sheldon prods.

"Then . . . I guess we'll confront them," Penny answers uncertainly.

"Penny, are you asking me to join you in a sting operation to bring down our respective significant others, while, at the same time, proving our moral and intellectual superiority over them?" Sheldon asks solemnly.

Penny flounders. "Yeah, I think so . . . no, definitely . . . that's what I'm asking you," she concludes decisively.

"Well, then you've got yourself a partner in criminal justice . . . or should I say downtown justice," Sheldon replies with a sly grin. "Wait right here, and I'll draft an agreement."

"Ummm . . . why don't we just shake on it, instead?" Penny asks hopefully.

"That sounds reasonable," Sheldon concludes, as he extends his hand formally for Penny to shake.

Penny tries not to be insulted by the fact that he's wearing an oven mitt, when he does it . . .