Stacking off with my pair of 4's

[cassette]

Villain is a good 22/17/4 player. He is very aggressive. This is a really weird line from him that I haven't seen before. What hand would he possible play like this that wasn't a draw?

I think this is a fold because there is a very loose player yet to act but if it was a tight player that we could trust to lay down a pair I would have loved to go for a hero call here.

No Limit Holdem Ring game
Blinds: $0.50/$1
6 players
Converter

Stack sizes:
UTG: $185.50
UTG+1: $83.48
CO: $111
Hero: $100.50
SB: $180.54
BB: $174.99

Pre-flop: (6 players) Hero is Button with 4[img]/images/graemlins/heart.gif[/img] 4[img]/images/graemlins/spade.gif[/img]
<font color="#cc0000">UTG raises to $4</font>, 2 folds, Hero calls, SB calls, BB calls.

Flop: 5[img]/images/graemlins/diamond.gif[/img] 3[img]/images/graemlins/diamond.gif[/img] 3[img]/images/graemlins/spade.gif[/img] ($16, 4 players)
SB checks, BB checks, UTG checks, <font color="#cc0000">Hero bets $12</font>, SB calls, BB folds, <font color="#cc0000">UTG raises all-in $181.5</font>, Hero folds, SB folds.
Uncalled bets: $169.5 returned to UTG.

Results:
Final pot: $52