River Raise Out Of Nowhere -- Call It?
 

Villain unknown.

Party Poker 5/10 Hold'em (6 max, 5 handed) converter

Preflop: Hero is SB with 6[img]/images/graemlins/diamond.gif[/img], K[img]/images/graemlins/heart.gif[/img].
<font color="#666666">2 folds</font>, Button calls, Hero completes, BB checks.

Flop: (3 SB) 9[img]/images/graemlins/club.gif[/img], J[img]/images/graemlins/heart.gif[/img], 2[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
Hero checks, BB checks, Button checks.

Turn: (1.50 BB) 6[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets</font>, BB calls, Button folds.

River: (3.50 BB) 5[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">Hero bets</font>, <font color="#CC3333">BB raises</font>, Hero ???

Also, who prefers c/calling the river for induced bluff equity?

Re: River Raise Out Of Nowhere -- Call It?
 

I think bet-folding is fine. Looks like rivered 2-pair, 87 or weirdly played something else that has you beat.
I dont even think you are ahead 10% after his raise.