What it do?? KK 3 way - getting pushed by a Nit

[johnnypokeher]

Villain is 15/3/.35 over 100 hands. Tight passive monkey

He sat down short stacked, and I just saw him play trip aces with weak kicker very passively to a pre flop raiser.

The other donkey still in the hand is running 45/2.5/1 over 60 hands. My notes say he is horrendous

With stack sizes what they are, and not too much on this board, is this an call or fold> Do these guys ever do this with anything I can beat?

CO is at seat 0 with $39.
Hero is the button with $116.95.
SB is at seat 2 with $56.35.
BB is at seat 3 with $100.
UTG is at seat 4 with $58.
MP is at seat 5 with $95.85.

SB posts the small blind of $.50.
BB posts the big blind of $1.


Hero: Kh Ks

Pre-flop:

UTG folds. MP calls. CO folds.
Hero raises to $4.50. SB calls.
BB folds. MP calls.

Flop (board: 2c 9h Th):

SB checks. MP checks. Hero bets $10.
SB goes all-in for $51.85. Hero???