A song by Canadian electronic music producer Joel Zimmerman (aka deadmau5). There are two versions of this song: one with vocals by MC Flipside and one without vocals. Both are high quality listening material :)

what you say to someone who is not your friend

An old acquaintance towards whom you are either luke warm or simply ambivalent and who you do not usually wish to engage in casual conversation. As a result your only interaction with this person is a brief "hi," "hello," or perhaps a (rhetorical) "what's up?" or "how's it going" when you happen to see them at the mall or encounter them awkwardly at the company watercooler.

Lol looks like I got in trouble again so I’m on urban dictionary one more time.
So ye Pc and whoever else of my friends decide to read this hi I’ll be back in a month.

Bye bye

A person you would say "hi" and "bye" to casually, but little more. Generally someone desirable as an acquaintance and not anything more.

From "This American Life"

People who say hi when you come to school/work and occasionally have sexual interaction with you

Saying hello to his little friend another term for how a guy masturbates, Jerks off, gets his jollies, and does the five-knuckle-shuffle.