This is a Hillbonics term. It's a fun, and more efficient, version of "What's up and shit?". Like when you ask someone, "What's going on?" or "What are you up to?". It's a great term because it's not annoying like that old "Whazzuuuuupppp?" that was overplayed in TV commercials and gets old when used by real people too often. It usually takes a little training to get used to saying it as a single word. But once you've got it down, you and your friends will use it often. It's a lot of fun witnessing new users get through the learning curve to get it to a single word. It's akin to watching a foreigner try to speak English when they're not used to it yet. It's so comfortable and efficient, that when used in a sentence as an example, the entire sentence is simply the one word. Get it?

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