NL50: Turned bottom set, Button takes weird line . . now what?!?!

[Gobias Ind.]

Full Tilt Poker - No Limit Hold'em Cash Game - $0.25/$0.50 Blinds - 9 Players - (LegoPoker Hand History Converter)

SB: $9.50
BB: $35.05
Hero (UTG): $69.15
UTG+1: $17.50
MP1: $15.95
MP2: $48.00
MP3: $47.15
CO: $134.60
BTN: $103.45

Preflop: Hero is dealt 8[img]/images/graemlins/diamond.gif[/img] 8[img]/images/graemlins/spade.gif[/img] (9 Players)
<font color="red">Hero raises to $2.00</font>, 2 folds, MP2 calls $2.00, 2 folds, BTN calls $2.00, 2 folds

Flop: ($6.75) 9[img]/images/graemlins/diamond.gif[/img] K[img]/images/graemlins/heart.gif[/img] T[img]/images/graemlins/heart.gif[/img] (3 Players)
Hero checks, MP2 checks, BTN checks

Turn: ($6.75) 8[img]/images/graemlins/club.gif[/img] (3 Players)
<font color="red">Hero bets $5.00</font>, MP2 calls $5.00, <font color="red">BTN raises to $13.00</font>,

Hero???