4th hand at the table, no idea what he´s up to. I got no other option, do I?

$0.5/$1 No Limit Holdem
5 Players
Converted at weaktight.com

Stacks:
UTG ($130.50)
CO ($100)
BTN ($47.50)
SB ($140.55)
Hero (BB) ($103.65)

Pre-Flop: ($1.50, 5 players) Hero is BB
UTG raises to $3, 3 folds, Hero calls $2

Flop: ($6.50, 2 players)
Hero bets $4, UTG raises to $11, Hero folds