"ßaaß" is a german word, that defines that someone or something is, cool; pretty; awesome, etc.

The first time it's been used was in german YT-P (Youtube-Poop) videos, later Best ofs or Ost Befs for the ßaaß kids, where the editor would take a word for example: "Was"="What" eng. and let it play backwards after the person says it.
(Was->saas=ßaaß)

when you're hungover as shit after a spending a night drunk as a skunk