JJ is one of my favorite "sleeper" hands as well.
When that third Jack hits, no one seems to think, in 25NL anyways, that you would have raised that much preflop with them, they will more likely put you on QQ-KK-AA-AK.

If someone bets hard when overcards come out though.... you have a decision to make.

Depending on the player, I typically fold in that situation unless I hit my set. If I hit my set though, it's time to get paid.