flopped trips OOP vs river shove

[Let_it_rain]

Thought it was just me and the BB hence the raise p/f
Villains stats:
pfr 0 VPIP 36 AF 0.76 W@SD 60% over 290 hands

PokerStars No-Limit Hold'em, $0.25 BB (4 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

Button ($39.60)
Hero ($36.70)
BB ($24.50)
UTG ($25.75)

Preflop: Hero is SB with K[img]/images/graemlins/heart.gif[/img], 7[img]/images/graemlins/heart.gif[/img].
<font color="#666666">1 fold</font>, Button calls $0.25, <font color="#CC3333">Hero raises to $0.75</font>, <font color="#666666">1 fold</font>, Button calls $0.50.

Flop: ($1.75) K[img]/images/graemlins/diamond.gif[/img], T[img]/images/graemlins/heart.gif[/img], K[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $1.25</font>, Button calls $1.25.

Turn: ($4.25) 9[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
Hero checks, Button checks.

River: ($4.25) 8[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets $4</font>, <font color="#CC3333">Button raises to $37.6</font>, Hero ??????

Final Pot: $45.85

So what do you do and why ?

[boycalledroy]

I bet $4 into the turn and check/call the river to a psb. As played I fold here because you gave him a free chance to catch up.

[pena]

Must fold, ~1:1 odds. Your trips are not ahead over 50% of a time, especially against an opponent that passive.

[Let_it_rain]

yeah I threw it away, couldn't make myself call.
Cheers guys