the ol' 3bet semibluff on the river.

PokerStars 5/10 Hold'em (6 handed) Poker-Stars Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

Preflop: Hero is BB with K, K.
2 folds, CO raises, 2 folds, Hero 3-bets, CO caps, Hero calls.

Flop: (8.40 SB) K, 9, 9 (2 players)
Hero checks, CO bets, Hero calls.

Turn: (5.20 BB) K (2 players)
Hero checks, CO bets, Hero calls.

River: (7.20 BB) 2 (2 players)
Hero checks, CO bets, Hero raises, CO 3-bets, Hero caps, CO calls.

Final Pot: 15.20 BB

Results
Hero has Kh Kd (four of a kind, kings).
CO has 8d 6d (two pair, kings and nines).
Outcome: Hero wins 15.20 BB.