I cautiously play hole card pairs like JJ, TT and 99 pre-flop. But, to put this practise into context, I do so knowing that they are middle pairs with a low 70-73 win percentage. When I do play JJ, TT and 99 pre-flop, I only call and I never raise. And, if someone raises pre-flop, my call will quickly turn to a fold. My strategy pre-flop is to see the flop cheaply in the hope that I can trip when the community cards hit the felt.
If nothing happens on the flop, I will check, hoping to get to the turn card without any further investment. If some one raises, I will fold because chasing trips past the flop can get quite expensive. However, if I do trip on the flop, depending on the cards on the felt, I will either slow play my trips against under cards to maximize profit or raise the entire pot against over cards to protect my trips.