Part: Part Five - Betting Before the Flop

The cold-call trap

Pre-flop
Blinds 100 / 200Pot 900 (4.5 BB)MPK♠J♠● 25,000 (125 BB)YOUto actUTG● 25,000 (125 BB)Solid openerraises 600 (3 BB)CO● 25,000 (125 BB)Aggro squeezeryet to actBTN● 25,000 (125 BB)yet to actSB● 25,000 (125 BB)posts 100 (0.5 BB)BB● 25,000 (125 BB)posts 200 (1 BB)D

A solid player opens under the gun. You're next in middle position with K♠J♠, and there are several players still to act - including a known aggressive squeezer on the cutoff.

Solid UTG opener, K♠J♠ in MP, aggressive players still behind. Best?

WhyK-J suited is dominated by the tight range a solid UTG player opens, you'd be out of position to the button all hand, and a known squeezer behind will often three-bet and force you off it anyway - you'd be paying to enter a pot you rarely get to play cleanly. Flatting into players yet to act is the worst choice with a hand this marginal.
What happensYou fold, and the squeezer duly three-bets behind you. Folding a hand that looks pretty but plays badly here saved you from a squeeze and a dominated pot out of position.
Cold-calling a raise with live players behind sets you up to get squeezed off the hand or dominated out of position. With a marginal holding, fold or occasionally three-bet - flatting is the worst of the three.

A cold-call with aggressive players still to act is a trap - flatting a raise invites squeezes and dominated, out-of-position pots, so lean toward folding or three-betting marginal hands instead.