JJ in early position in third level, I limp, what happens next depends on who raises, how big their raise is, how much they can hurt me, how big or small my stack is, if no one raises it depends on the flop and who else is in the hand. Limping makes it easier to get rid of if you get action from someone you don"t want involved with or when an ugly flop hits the board.
Although I have limped, hit my jack on the flop and still lost all my chips. Actually I take it all back, fold, fold, fold!!!!