In order for the shit exchange to properly take place, the receiver must be performing a three-point balance on his/her head. The "shitter" then takes a massive dump on the receiver's asshole and then uses a large wooden dowel to push the shit into the receiver's ass.

Optional additions to the shit exchange can include:
-oral cleanup
-re-shit exchange (receiver becomes shitter, and performs the shit exchange with the original shitter's shit back into the shitter's ass)

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