One night, at a job I had only been at for two weeks, I backed my car into a co-workers truck. I got out, looked around, nobody came out of the office, so I high tailed it. I know, I'm an ass.
I was also running late for a booty call, so, anyway, when I got home I looked at my car in better light I noticed that I had busted out my tail light. So, knowing there was evidence behind I decided to go back and fess up (after I was done with business of course)
When I get back to the office and go in I tell the coach/lead/supervisor on duty what had happened. When I described the truck to her she started laughing hysterically. We went outside with several people following. I pointed to the truck and the (which I honestly hadn't noticed at first) the substantial dent in the back of the truck.
This only caused her and the others to laugh even harder.
"That dent," she advised me, "is the dent I put there when I backed into his truck. If you hit him there as well, you can't even tell. If I were you, I'd never tell him about it. He left it parked here tonight because he went to the bar next door and was too drunk to drive it home."
And she turned around and walked back inside. As far as I know, he never found out.