[Obliky]

:Grunch:

I think this is fine, with big pairs you often tie yourself to a showdown and with the turn & river cards being blanks there is no way you are folding.

CO probably thought you were on a draw and so wanted to see what the next card was before betting again..thats the only logical reasoning i can think of behind the turn donk.
Depending on the player it may even be right to raise the turn (actually this might be the best play here), but with no reads i guess calling down is ok.