Oopsident Share definition Flag Slang, combination of oops and accident. She had an oopsident with her breasts popping out of her low cut neckline shirt. It was an oopsident, I swear! Oopsident by BallsOutBetty April 7, 2009 0 0 Get merch Get the Oopsident mug. Buy Now β $32.95 See more merch