[23Suited]

If you flat called pre you could c/f on this flop...

but when you are already in this far I agree with Djk123 that you have to shove him here especially considering his rather unconventional line...

I dont think I like a preflop shove... while it is basically the same play it has different merits then shoving as a c-bet on the flop here... basically you allow your opponent to play far to perfectly against you if you shove pre because he is just folding unless he does have a real hand this time...