[registrar]

We fold to a shove.
We call a weak bet.
We make a straight or check the river if we don't.

I'm not mad keen on doing any of the above but then I don't bet the flop into a good LAG three-way because he's not going to fold enough and not going to call enough when we hit on a later street and because there's all sorts of ways/cards that will see us pay off OOP.

Edit: as others said, we can also bluff river scare cards (not that I would) or open shove the turn (which I might).