Folding flop with top pair K-kicker

[private joker]

This is standard, right? The only guy I have a read on is UTG+1, who is one of the worst players I've ever seen. Over-aggressive and loose. Everyone else is unknown.

Party Poker 3/6 Hold'em (10 handed) converter

Preflop: Hero is Button with K[img]/images/graemlins/diamond.gif[/img], 9[img]/images/graemlins/diamond.gif[/img].
<font color="#666666">1 fold</font>, UTG+1 calls, <font color="#666666">1 fold</font>, MP1 calls, MP2 calls, <font color="#666666">2 folds</font>, Hero calls, <font color="#CC3333">SB raises</font>, BB calls, UTG+1 calls, MP1 calls, MP2 calls, Hero calls.

Flop: (12 SB) 5[img]/images/graemlins/club.gif[/img], 3[img]/images/graemlins/heart.gif[/img], 9[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(6 players)</font>
<font color="#CC3333">SB bets</font>, BB folds, UTG+1 calls, <font color="#CC3333">MP1 raises</font>, <font color="#CC3333">MP2 3-bets</font>, Hero folds