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?

WhyFold. Cold-calling here is the trap: K-J suited is dominated by a tight UTG range, you'd play out of position to the button, and the aggressive squeezer behind will often three-bet and blow you off the hand. With a marginal hand, flat-calling into players yet to act is the worst option - fold (or, rarely, three-bet), but don't cold-call.
What happensYou fold; the squeezer indeed three-bets behind.  You saved yourself a mess.
Cold-calling a raise with players left to act invites a squeeze and a dominated, out-of-position pot. With a marginal hand you fold or three-bet - flatting is the worst of the three.

Beware the cold-call: flatting a raise with aggressive players still behind invites squeezes and dominated spots - prefer folding or three-betting marginal hands.