It means something is WAY BETTER than good, ok, excellent, awesome,bussing,or an anime chick (if your a goddamn simp), or used to describe a hot babe.
(ex:) Haden: DaMn
Audriana: What?
Haden: This season of MHA is BuBbLy BuSsInG! Especially how sMeXy Setsuna looks~
Audriana: Haden, remember we are together and you have over 15 anime waifu body pillows.
Haden: But she so bubbly bussing HaWt
Audriana: Another step to ending our relationship.