bustin Share definition Flag an air performed at the top of a wave on a surfboard or other wave riding device rusulting in the fins leaving the water. "whoa bro, i was in the surf today and the waves were hollow and everyone was bustin'" bustin by Spicoli420 October 23, 2007 0 0 Get merch Get the bustin mug. Buy Now — $32.95 See more merch