NL 100 overpair vs bizzare overbet

[That Foreign Guy]

Hero - $104
Villain - $88
Random Shorty - $19

Villain posts $0.50
Hero posts $1
Dealt to Hero Q[img]/images/graemlins/heart.gif[/img] Q[img]/images/graemlins/diamond.gif[/img]
Shorty folds
Villain Calls $0.50
Hero raises $2
Villain Calls $2

Flop (Pot = $6) J[img]/images/graemlins/heart.gif[/img] 9[img]/images/graemlins/heart.gif[/img] 4[img]/images/graemlins/spade.gif[/img]
Villain checks
Hero bets $5
Villain Raises $88

Hero WTF???

No reads, only about three hands on villain (pretty standard raise fold HU stuff). This site does offer an allin button next the raise button, so this could be a misclick, but still...

FWIW - I think for less money I call in a heartbeat, without the knowledge that there is an allin button (which can be turned off in options) I fold in a heartbeat.