Merriam-Webster Online Dictionary
gotcha (noun) an unexpected usually disconcerting challenge, revelation, or catch , also an attempt to embarrass, expose, or disgrace someone (as a politician) with a gotcha
Merriam-Webster Online Thesaurus
gotcha (noun)a danger or difficulty that is hidden or not easily recognized
SYNONIMS:
booby trap, catch, catch-22, gimmick, gotcha, hitch, joker, land mine, snagRELATED WORDS:
snare, trap, trip wire, web; hazard, peril, risk; bomb, bombshell, kicker, surprise ( surprize); bait, decoy, lure