To be near impossible to swindle, cheat or conned out of somethingfinancial. See noun 'bump' (London slang version)
To be savvy enough to avoid paying too much for an item(s) and or service(s)
They are trying to bump up the prices because we are tourists but they don't knowI've been here eight times, I'm unbumpable
I've been dating Betty for a couple weeks now and she asked for an unfumpkin. I was like, "girl there isn't enough mouthwash in the world for that shit."
i am so freaking tired of hearing that ralph in tampa FL is undumpable, get rid of her arse, you have better things waiting for you
gawd, dont you hate it when you are dating a guy and he lives with a freaking RALPH who is undumpable for some unfortold reason...must be a golden vay-jay-jay