I’m not going to tell it as well, but:

The guy takes out a frog, and tells the blonde “this is no ordinary frog! It can do tricks!”

“What kind of tricks?”

“Well, he can lick pussy.”

The blonde wants to see, so she invites him over and takes off her clothes. The guy sets the frog down on the bed.

Nothing happens.

The guy says to the frog, “You’ve forgotten how to do it, huh? Here, let me show you how it’s done.”