Adding rigidity to your lift form: suck in your anus

Any lift from squat to deadlift to bench press to standing barbell bicep curl requires a certain amount of rigidity and torso tension to complete a successful lift.

One way to add more stiffness to the lift is to suck your in your butt hole.  It forces you to contract the glutes hard and flex  your quads, and when this happens you have a more stablebase to lift from.