The famous car-on-fire incident as referenced in my fic Worship!
Doctor Rodney McKay flinched at the sound of Zelenka's voice and turned to face him with a face that was so patently guilty that for a moment the Czech wondered if he was playing a joke.
"Rodney, what are you doing in my lab?"
"Well, ah, there was a, a thing."
"A thing?" Zelenka repeated, more and more confused.
"Yeah, I left a thing behind and I, I came back to get it."
"Well, I haven't seen anything belonging to you lying about. What did it look like?"
Rodney waved one hand dismissively. The other was tucked behind his back. "You know what, never mind, it wasn't an important thing, I probably left it in my room anyway. I'll go look for it there."
"Rodney," Zelenka said sternly. "What's in your hand?"
"Nothing." Rodney waved his empty hand in front of Zelenka's face, almost knocking off his glasses.
"Your other hand, Rodney."
The look on his face was pure 'busted.' "Yes, ok, so I'm borrowing your new battery-thing, but I'll give it back!"
"It's not a battery, it's a miniaturized naqahdah generator, and you weren't borrowing it, you were stealing it."
"I was gonna give it back!"
Zelenka rolled his eyes. Trust McKay to sound indignant about being caught stealing. "What did you want it for, anyway?"
"Oh. No reason."
"Ok, you remember how Sheppard beat me last time we raced?"
"Doesn't he beat you every time?"
"No! Well, maybe."
Zelenka did remember something vaguely like that. "You want my generator to make your remote-controlled car run faster?"
"No," McKay announced triumphantly, "I want it to win the pot."
"The pot?" This conversation was just making less and less sense.
"Yeah. I said Sheppard's car was better, he said I should just change mine… Long story short, we agreed that each of us would go off and upgrade our cars, and race them again. Ronon went and spread it around, and now everyone is placing bets. The winner of the race gets half of the money."
"So you want my generator to make your car run faster."
"Well… I guess."
"How much money do you stand to win?"
"A lot of people have gotten in. I mean, there's not a lot to go out and buy in the Pegasus galaxy. Couple of hundred at least."
"I want half."
Zelenka grinned. "I'll loan you my generator, but if your car wins, I want half."
"But that means I only get a quarter!"
"You'll get to gloat. We all know how much you like that."
"True," McKay mumbled. "Alright. But you have to help me attach it to my car."
Doubts suddenly rose up and struck Zelenka around the face. "I should probably warn you, it is a little unstable–"
"I don't care, it just has to run long enough to beat Sheppard."
"You don't think that's a short-sighted attitude?"
"The attitude of a champion, my friend. The attitude of a champion."