This hand touches people in bad places and is wrong

[B Dids]

Party 5/10 6 max.

I'm in the SB with K [img]/images/graemlins/club.gif[/img] 2 [img]/images/graemlins/club.gif[/img]

loose passive limps UTG.

unnoteworthy but not good guy limps on the button.

I complete.

Solid seeming but mostly unknown BB checks.

Flop

8 [img]/images/graemlins/club.gif[/img] J [img]/images/graemlins/heart.gif[/img] K [img]/images/graemlins/heart.gif[/img]

I bet, BB calls, Button calls

Turn

6 [img]/images/graemlins/spade.gif[/img]

I bet, BB calls, button folds.

River 8 [img]/images/graemlins/heart.gif[/img]

What's my action?