That's one you owe me.
I let you slide.
I couldn't fax you the bunny.
It goes against my pride.

The story:

Actually, this was a friend of mine, Eliza. We'd been playing a lot of Johnny Cash, and she had been looking more and more puzzled whenever this song came on. Eventually she asked us why he'd do something like that. So now when we do the dirty on someone, we refer to it as "faxing them the bunny."