Sleeping With a Friend

friend: noun
1. a person attached to another by feelings of affection or personal regard.
2. a person who gives assistance; patron; supporter.
3. a person who is on good terms with another; a person who is not hostile.

It's clear what the definition of a friend is. So then what happens when someone crosses the line of friendship and explores a different kind of relationship?

That's when they're sleeping with a friend.