Yo!

"Yo!" is a very informal, familiar greeting, kind of like "Hey!" It can be used when you don't know or can't remember someone's name and want to get their attention. Another possible use is as a shortened form of "your." It originated in African American Vernacular English (AAVE), but has now been adopted by speakers of all ethnicities. It is interesting to note that "yo" also means "I" in Spanish, a language widely spoken in the U.S., but in American English it doesn't mean that, nor is it related.

Examples:
-Yo, come back here!

-Get to work, yo!

-Yo mamma!


True story:
I'm white. Sometimes when I call my dad on the phone and he sees it's me on the caller ID, he answers, "Yo!"