Call or fold the river? No reads but I doubted he was any good. It's 6-handed and I've listed the stack sizes that matter.

Hero ($98.85)
CO ($61.37)

Preflop: Hero is UTG with J , K.
Hero raises $4, 1 fold, CO calls $4, 3 folds.

Flop: ($9.50) 3, Q, K (2 players)
Hero bets $7.00, CO calls $7.00.

Turn: ($23.50) T (2 players)
Hero bets $15.00, CO calls $15.00.

River: ($53.50) T (2 players)
Hero checks, CO bets $19, Hero ...?