I Would Pay You 10
It is her husbands best friend and she invites him in. Since she is in her bathrobe the man says to her "you have the nicest breasts". She says "thanks but my husband would be mad if he heard you".
He replies "I would pay you $10 just to see one of them". She thinks for a minute and decides to do it.
He says "Wow that is the most perfect breast I ever saw....I will give you another $10 if you show me both at the same time".
She does it, and he gives her the money. The friend leaves and her husband comes home. She says "your best friend just stopped by". He answers "Great did he leave the $20 he owed me"