Yeah, that's what I thought. Maybe he limped in with JT, J9 or Jxs. So I folded.

He sure represented trip jacks. But wasn't it a bit risky for him then to give a free card twice? He probably knew that anyone betting on the turn would have an ace, so why not try a check-raise bluff? Also, was the half-pot sized bet on the river a good value bet (probably not since I folded)?