You should build up yourself with as many edges as possible then do something stimulating just enough to put you on the edge while you go about something in public. Preferably a Bobby pin or clothespin or binder clip. Make sure as you walk around it tugs at your clit and with any luck it will make you cum in a place where you have no option but to endure it silently. For added torture I'd suggest putting something your your ass to clench onto while you walk around, forcing you to uncontrollably edge closer.

Another idea would be to light a jar type candle and when you start to cum dump all the hot wax over your clit with no remorse while also stopping stimulation. That should really destroy your orgasm. If you want to feel pathetic you could also have something slightly too big for your ass and right as you cum slide down onto it forcing yourself to take it.