Holiday, usually referring to school holiday. A slang usually used by immature youngsters over instant messaging.
Kid 1: Yeahoo hollz baby!
Kid 2: Yeahhh no more school! I love hollz!
A synonym of holla, yay, or yes totally. Additional "z"s can be added to the word depending on how happy or white girl wasted you are.
Me: We're going to the bar tonight because there are $4 dollar Long Island Iced Teas.
Michael: Hollzzzzz, let pre-game before we go!