I've probably done stupider things when I was new to the game (for the first week or so I thought QKA23 was a straight), but this is the stupidest thing I've done in recent memory.
No-Limit Hold'em Tourney, Big Blind is t50 (5 handed) FTR converter on zerodivide.cx
Preflop: Hero is MP with Kh, Kc.
UTG calls t50, Hero raises to t200, 2 folds, BB calls t150, UTG calls t150.
Flop: (t625) Jc, 4d, Th (3 players)
BB bets t695 (All-In), UTG calls t695, Hero folds.
Turn: (t2015) Tc (2 players, 1 all-in)
River: (t2015) 7s (2 players, 1 all-in)
Final Pot: t2015