"You owe me 78 dollars" is a phrase used when sarcastically demanding financial compensation, when it is completely inappropriate. Legend has it that the amount of $78 is based on a true story, where a bill for car maintenance was split between the members of a road trip, to fix damage that occurred a year after the trip.
Jack: Aw man, I just got a photo radar
! You owe me 78 dollars!
Kate: Why?! You're the one driving!
Jack: Yeah, but you're in the car too. I'll send you a paypal
Hugo: Dude, try the sushi. It's awesome.
Sawyer: Okay, but if I don't like it you owe me 78 dollars.