Here’s a list of some shirt benching verbiage and what they mean to your bench:

Tucking: When bench pressing assisted, we need to tuck our elbows into our sides on the descent. This takes some of the tension out of the chest plate of the shirt and allows you to touch the bar at one of the highest points of your body. Even though you’re tucking your elbows in, you still need to keep the bar over your elbows for stability and pressing power.

Flaring (the opposite of tucking): During the ascent of the lift, you need to flare the elbows back out to increase the tension on the chest plate of the shirt. This creates more of a carry through effect for the shirt.

Lockout: This is simply the completion of the lift. This should happen with the elbows out and over the neck to face area. This allows for more muscle and shirt involvement and the ability to lockout heavier weight.

Chopping: Chopping is when you allow the bar to get behind your elbows during the descent of the lift and hit higher on your body than at the sweet spot. When you press, the natural tendency of the bar path is back on to your throat. Your ability to complete the lift technically is compromised.

Dumping: Dumping is when you allow the bar to drift toward your feet too much on the descent of the lift and it gets in front of your elbows (usually happens when you’re struggling to touch a weight). This will either end in a stalled lift or the weight will crush your stomach, or already swollen liver.

Reaching: Reaching is when you try to touch the bar on the descent by pushing your heels down, squeezing your butt cheeks together, and pushing your stomach (or liver) up to meet the bar. You shorten the range of motion, which allows you to touch a lighter weight or use a tighter shirt.

Everyone’s goal (I would imagine) is to lift the most weight possible, which necessitates using the tightest shirt possible. Proper form, which includes tucking, flaring, and reaching as well as proper lockout, will allow you to do this. Record yourself on video, and learn to feel your way through this. Once you learn the motions and the feel, you’ll exceed even your own expectations.