Indecent Proposal

A film where a rich guy (Robert Redford) offers $1 million dollars to a poorer guy (Woody Harrelson) to sleep with his wife (Demi Moore). And so inspired millions of the similar drunken conversations to the effect of "I'd let mine do it for a Six pack of beer if she promised never to come back" - Harsh, that's harsh.

This film also inspired the immortal question posed by celebrity TV interviewer Dennis Pennis to Demi Moore "If it was tastefully done and vital to the script, would you ever consider keeping your clothes on in a movie?".