Party Poker No-Limit Hold'em, $ BB (5 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

Hero ($1822.01)
MP ($1550.96)
Button ($534)
SB ($492.50)
BB ($300)

Preflop: Hero is UTG with T, J. SB posts a blind of $3.
Hero raises to $21, MP calls $21, Button calls $21, 2 folds.

Flop: ($72) 6, J, 8 (3 players)
Hero bets $60, MP calls $60, Button folds.

Turn: ($192) 6 (2 players)
Hero bets $150, MP calls $150.

River: ($492) J (2 players)
Hero checks, MP bets $375, Hero raises to $750

Final Pot: $1617

Villain is very aggro. Who likes river check?