SBSI Share definition Flag Acronym: Side-By-Side InsertionA dude and his bro banging chicks next to each other. Bro #1: Dude, wanna get some honeys and SBSI tonight?Bro #2: Hell yeah, double the titties! SBSI by TheChosenOne83 October 19, 2011 0 0 Get merch Get the SBSI mug. Buy Now — $32.95 See more merch
