wassu dude

A mixture of Wassup and dudes, which put together forms wassu dudes. Can also be found as wassup dudes.

Urban dictionary meaning for wassup: short form of "what's up"- simplified as a form of greeting, as in "hi."
Urban dictionary meaning for dudes: A word that americans use to address each other. Particularly stoners, surfers and skaters.

Therefore ur basically saying hi in a "cool dude" way