I've been on the receiving end of that in sparring. But the satisfaction of making me almost fall backwards in that case, was soon replaced by a surprise of my flappning hands slapping my opponents right accross the throat and face - not on purpose but as a reflex to regain balance - which i did recover, but the opponent wasn't prepare to block my reflexive slap and the range was close. After that, I was rather embarassed not for almost tripping, but for accidently slapping my opponent across the throat and face.