I personally never use this play, but a lot of people will LRR aces or kings in full ring when they are UTG or UTG+1 to trap. This only works at an aggressive table with lots of preflop raising, where you know you'll get a chance to 3-bet; in other words you have to be sure someone is going to raise so it's not just 1 bet to play preflop. The idea is to get limpers, then trap them into cold calling 2 more bets before the flop.

IMO this reasoning is stupid; if the table is alreayd laggin it up, you don't need to LRR to get action on a big hand. They'll cold call and 3-bet with the same hands they'll limp and raise with anyway.

Hope this clears up some confusion,
Steve

P.S. In my experience (aka small sample size) I have only seen people do this with AA or KK. I'd be on the lookout if I were you; this is where PT and a HUD come in handy.