100r Vs. Gigabet

[Ben86]

lost the hand history but it just happened this is almost exact.
I have 25k, gigabet has nearly the same at 600/1200/XXX

I raise A [img]/images/graemlins/heart.gif[/img]T [img]/images/graemlins/heart.gif[/img] UTG +2 to 3k and gigabet flats from Hijack.

Flop: (Pot ~9K) J [img]/images/graemlins/club.gif[/img]8 [img]/images/graemlins/heart.gif[/img]8 [img]/images/graemlins/spade.gif[/img]

I cbet 4500, gigabet shoves for like 20k more. What does he do this with?