When you or your golf partner goes to reach for their wedge in their bag and realizes they left it on the green two holes back.

Noun: a friend who is usually only called upon by a friend when a more primary/prominent friend is unavailable.

Taken from the term “second string” in an athletic competition situation. In football, if the star quarterback gets injured during a play, the second string is called off the bench to replace him/her. A “Second String Friend” is essentially benched until needed, if ever.

Synonyms: Plan B, Second Choice, Secondary Friend, Benched Until Needed

A woman with a very flat chest, such that it resembles her back. Only the nipples give it away.

A "twoback" is a woman with no visibly protruding breasts. See also: "flat as a board."