SuBROnatural Share definition Flag 1. When something is so BRO that it is unnatural.2. Four popped collars. Dude that party last night was SuBROnatural...there was like ten kegs. SuBROnatural by El Broheime April 3, 2010 0 0 Get merch Get the SuBROnatural mug. Buy Now — $32.95 See more merch