Pants-On Friend

A friendship where there is no sexual contact. Used in modern dating to help determine someone's availability.

This is James, he is my Pants-On Friend

Pants-Off Friend

A person who's company you enjoy while also being able to engage in a healthy, non-committal sexual relationship

Adam is a confirmed bachelor. He has many friends. Many are Pants-On. However, from time to time he does have Pants-Off Friend.