Wow, Jx of clubs? Obviously not JQ because he didn't hit his straight. So he called you pre-flop with Jx suited and then called a flop bet of most of the pot with nothing but backdoor draws? I hope you made a note that he was fishy. Either that, or he's kind of a maniac who relies HEAVILY on his ability to bluff people out of pots. If he had J9 of clubs, I can kind of understand the turn, because he did pick up a powerful draw - but usually I would prefer to make that move with two cards to come, because of the equity edge. In this hand, even if he assumes all his outs are live, he's still behind. I guess he just sensed you were weak by not re-raising him and decided to go ballistic on the river if he missed, which worked out excellently for you, as it happens. Good call.