Folding top pair to the turn CR.

[stigmata]

I would usually call here, sometimes the donkbet is a good hand like AK/AQ/AJ/AT, but completely unconnected with the flop. If he has 2 pair you have hidden outs. And like Jeff says, could be pair+draw combo. I think these scenarios + metagame considerations is enough to often call down in these over-aggressive / tricksy games.

[catlover]

Agree this is a call down situation. In addition to possibilities stated by the other posters, you have hidden outs if he has A2 or A4.