Disclaimer: I don't own Harry Potter or BtAS. No money was made from this story.

Summary: Harry Potter xover. One-shot follow up to "Humor Me". The Weasley twins pulled a prank on the wrong villain. Now the Joker's back for the last laugh.

A/N: This is a sequel to my one-shot xover "Humor Me", and I recommend you read that story before this one. This is set a few months afterwards. Enjoy!

"Laugh it Up"

"Mum's right, you know," Ginny stated, hands on hips as she tried to restrain the smirk on her face. She wasn't in the best of moods, having spent the last two hours hunting down the experimental Exploding Spiders that the twins had accidentally released throughout their entire store. "One day, you two really are going to play a prank on the wrong person. First you taunt the Dark Lord with shotty advertisements. . . ."

"Shotty! Those were brilliant!" George shouted from the back of the joke shop.

"Then," Ginny continued, "you plant your enormous "stink doxies" throughout the entire Ministry building."
Fred's voice sounded from beneath the counter where he was on hands and knees, wand and net ready. "That was a political statement, my dear little sister. If I remember correctly, it was also a distraction for the Order members working inside."

The young witch rolled her eyes. "And now," she insisted, "you take your popularity to a new level by aiding in the capture of a muggle villain."

"Your point, my little gin and tonic?" George asked.

"Don't you think you're pushing it a bit far?" she asked, aspirated.

"Shows what you know about business. . . ."

"Honestly, sales have never been higher," Fred added, a sudden whomp following his reply. A moment later, the twin appeared head first, wiping off his wand, his face and hair dripping purple goop.

Ginny shook her head. "Will the two of you never learn?"

Her answer came from two mouths. "NO!"

"Fine! If you refuse to listen to me, then I think I'll take my leave. You can finish cleaning this place on your own—though, you'll probably just call up Verity in the morning to do your dirty work," Ginny snapped, turning tail and strutting toward the back exit. "Adieu!" With a POP, she apparated away, assumingly back to the Burrow.

"More and more like Mum every year," Fred stated, gesturing to where his little sister had just been standing. "You'd think she'd lighten up for her seventh year at Hogwarts, pull a few tricks herself, but instead she's beginning to take after Hermione. She didn't even help us find the last. . ."

A splat sounded from the other room. "I found it!" George called.

He walked into the main shop, his blue robes covered in pink slime. "I think our crafty eight legged bombs are going to do splendidly in the Christmas catalogue," he commented, pointing his wand toward himself and his brother, in turn, to clean up the spidery mess.

"I'm not sure about the magenta one, though," Fred commented. "I much preferred the orange—more popular with the younger wizards, our big buyers."

"Oh, but we can't leave out the ladies like that!" George smiled.

Suddenly the front door exploded in a cloud of smoke and debris, shattered pieces of wood and glass covering the main shop floor. George blinked in surprise, lifting his wand and hunching down behind the counter beside his brother.

"No, no, boys. Put down the firewood before someone pokes out an eye," called a high, laughing voice.

The barrel of a gun appeared through the smoke, pointed straight at the two wizards. A figure appeared behind the weapon, a wide smile coming into view as the smoke fell. The twins felt their blood run cold as they recognized the man at the door as none other than the Clown Prince of Crime, The Joker.

"Why does Mum always have to be right?" Fred hissed, his own wand faltering slightly as a set of goons and a pretty jester appeared at the villain's side.

George's jaw set at the sight, and he lowered himself further down, calling out The Joker from his hiding spot. "Welcome to Weasleys' Wizard Wheezes! I'm sorry to say that we're closed that the moment, but if you'd like to come back tomorrow at eight sharp, I'm sure. . . ."

A shot rang out, ringing a hole in the wall above the counter. "Or maybe you'd just prefer to take a catalogue home with you?" George asked.

Fred elbowed his brother in the side, mouthing a very frantic 'DON'T MENTION CATALOGUES' to his twin. "Is there something we can do for you, Mr. Joker?"

George peeked over the counter. "Yes, indeed, we feel just awful about that whole 'arrest' thing. Honestly, our lawyers were the ones to suggest that we put a clause in the catalogue to prevent liability lawsuits. Who would have guessed that you had less than innocent intentions for the items you ordered?"

Fred raised a brow that stated, "Lawyers? As if we'd ever hire a lawyer. . . ."

"Oh," the Joker said, sadly, "in that case. . . ." A series of gunshots rang out as he shot the register to bits. When the noise died down, his manic laughter sounded through the shop. "I've got to hand it to you two. You definitely gave me a good laugh."

"What we live for," George called.

"And we're hoping to continue," Fred interrupted.

"Living that is," George finished.

"Come out and maybe we can come to some sort of arrangement." The twins could hear the Joker approaching. "I'm not here to kill you—actually, I think you may have a consolation prize for me, if those creative little toys you had for sale actually exist. After all, I did have to cross the great pond to get here."

"And Mista J gets pretty grumpy when he travels," the jester chirped.

Without another word, the twins rose as one, not to attack, but to display some of their newest handy work. "Mr. The Joker, of course we owe you for your travels!" George said, gesturing out across the store.

"You are, quite possibly, our most valued customer," Fred added.

"At the moment," George continued. "And we honestly did want you to be included, nay, made head of the new Prankster's Paradise line of goods."

"You are our inspiration!"

"How could we think of jokes so insane without. . . ."

"An equally insane role-model," Fred finished. "So, without further adieu—I mean, you've traveled such a long way to see us—we present you with. . . ."

George paused, suddenly realizing that he hadn't thought this one through. "Anything you want," he stated, offhandedly. "Including all of the items you originally placed on your order list."

"Does this mean I can finally get the Wonder Witch . . .? Ouch!" The Clown Princess of Crime pouted as the Joker withdrew the elbow he'd jabbed into her arm. "Sorry, puddin'," she frowned.

"Well, boys, you've caught my attention," the Joker said, his grin even larger. "And depending how this little shopping extravaganza goes, we might just have to come to a more permanent trade agreement."

"I assume you'll be paying in cash after tonight?" George asked.

The Joker lost his smile a bit. "I don't think I mentioned payment."

"Forgive my brother," Fred said. "The Head of Prankster's Paradise does not pay, silly George."

George bowed slightly before making his way to the end of the counter. "Fred's right. Silly me." He glared at his brother. "Mr. The Joker, I believe most of the items you're looking for are located in the back area—where we keep the most up to date, experimental. . . .Pranks."

"Not for the kiddies, no sir," Fred smirked. He led the group past the displays into the back room of the shop. "Come one, come all," the wizard hastened.

The Joker and his goons huddled in, automatically raiding the shelves. "Tell me what you have, boys," the clown stated, delightfully nodding to Harley as the jester filled a bag with boxes of magic goodies.

"Well, even a business man such as yourself is sure to run into problems every once in a while," Fred stated.

George grinned, "And what better way to get rid of a 'problem' than a good distraction?"

"I'm interested," the Joker said, gun against his hip as he listened.

"A few years back we developed a handy, if somewhat primitive little tool." George pointed to a relatively small horn hanging from one wall. "This lil' fellow will take off, opposite the direction that you're running in and emit a loud noise. And, they come in bulk."

"Drawbacks," Fred added, "are few but important. The horns only last a few times because, well, let's face it, eventually the guys chasing you are going to realize that noise is nothing."

"However, recently, my brother and I have been working on something new for those who might find themselves in a worse bind."

"Sounds like that might be a bit more useful for a man as sought out as myself," the Joker agreed.

George paced across the room. "Well, so far, the distraction itself has not been able to last for more than five minutes."

"Which, at least, is plenty of time for a clean getaway," Fred said. "It's foolproof during that time, thankfully."

"We even managed to fool our own mum with it."

"Quite the accomplishment," Fred noted.

The Joker raised a brow. "I'll take a dozen. Where is this little distraction you're talking about?"

The twin spoke together, "In front you, you big lump!"

With that, the doors to the front of the shop slammed closed and laughter sounded from the other room.

"What is this?" The Joker snapped. He jumped forward, meaning to grab one of the twins by the scruff, but, instead, he 'fell' through the wizard.

"A damn good distraction. A non corporeal image that simulates our true forms in behavior," Fred answered, grinning down at the body half-way through him. "You see, as we led you into a trap, our makers slid out from behind the counter, sending an owl to the Ministry and, as you witnessed, slamming the doors in your face. I do believe they're quite proud of us."

The Joker sent his men forward to shoot out the doorway, but it refused to budge.

George's image added, "And I would like to also mention that they are most likely notifying your dear Batman as to where he and the Gotham officials can pick you up. I should say, the newspapers will love this story—or at least the wizarding news will."

"We don't mind tell you as much," Fred added, "because, frankly, we're planning to wipe this memory from your head.

"Cheers!" the twins grinned, their forms fading away.

The Joker let out an animalistic growl, shoving his own men into the shelves.

"I told you we should have left them alone, Mista J."

"Oh, shut it, Harl," the clown frowned, sliding to the floor after hearing the sound of chuckles from the front room. "Laugh it up, boys. But you better hope I don't remember this!"

The Jester let out a nervous chuckle. "Well, ya gotta admit—they got us, puddin'."

End Notes: So, not very funny but interesting, right? Anyhow, review me if you like.