The CO opens, you 3-bet on the BTN, and the CO calls.
The 3-bet makes the pot big and the stacks shallow, so the stacks go in easily after the flop. Example: pot 17.5bb with 92bb behind, so the SPR is about 5. Even a small 33% bet on the flop gets the stacks in by the turn and river. Overpairs and top pair with a strong kicker can get the stacks in even when raised.