Penance?

A new priest is introduced to a church. The old priest shows him around and tells him that he can do the confessions today.

So he does it and a man comes in and says: "Father forgive me for I have sinned. I had anal sex with my girlfriend."

The young priest doesn't know what he should give him as penance, so he goes to the altar boy and asks him: "Hey, what does the old man give for anal sex?" - "A Mars bar, sometimes a Snickers..."