100nl - KK versus river overbet

[11t]

2nd orbit, no reads. Standard?

PokerStars No-Limit Hold'em, $1.00 BB (5 handed) FTR converter on zerodivide.cx

SB ($71.45)
BB ($110.15)
UTG ($24.40)
Hero ($103.60)
Button ($277.35)

Preflop: Hero is MP with K[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/heart.gif[/img].
<font color="#666666">1 fold</font>, <font color="#CC3333">Hero raises to $4</font>, <font color="#666666">2 folds</font>, BB calls $3.

Flop: ($8.50) 2[img]/images/graemlins/heart.gif[/img], 8[img]/images/graemlins/diamond.gif[/img], Q[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
BB checks, <font color="#CC3333">Hero bets $6</font>, BB calls $6.

Turn: ($20.50) Q[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
BB checks, Hero checks.

River: ($20.50) J[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">BB bets $25</font>, Hero folds

I figure I am readless and all I beat is a stone cold bluff