Number One - S1-E24
Continuity mistake: When Randy is scratching off the joke lottery ticket, the amount of scratched-off material left on the ticket changes between the three close-ups. One shot shows that the ticket was rubbed and not scratched (the area revealed has a haze to it).
Answer: The premise of the show is he atones for mistakes he did in the past. Winning a car for Joy probably atones for something he did wrong regarding her in the past.
Rob245