Lewd tooth-fairy?

I grabbed three singles from Jeff's wallet last night to replace Kenny's extracted eyeteeth under his pillow.

This morning, Kenny showed me the back of one of those singles and I've never seen anything like it before: a "B" handwritten before and an "R" handwritten after the "ONE." Jeff says it's a strip club single. Even so.

I simply told Kenny that it's a bad word and that I'd switch the dollar for him.

But Tim traded him for it before I could.

How do I explain all this without blowing the tooth-fairy's cover?!