In Call of Duty: MW2, when someone puts a Riot Shield on their back and goes prone so they can not be knifed.

When you eat dirt for the first time and leave your family to build a shack in the woods

The art of hiding an erection while sitting and leaning one's upper torso at a 45 degree angle betwixt one's chest and lap. The owner of said erection then proceeds to arch their back in such a way that makes them appear to be sitting upright. This causes said erection to recede into the body causing a "turtle shell" effect.

What happens when you hold your poop for too long. When you finally sit down on the toilet, you let loose only to realize that it may have been on the verge of popping out, and that you probably had less time to wait than you thought.

V. The act of taking someones backback when they're not looking, taking everything out of the main pocket, turning the bag inside out, placing everything back in, zipping it up so as the zippers are on the inside making it difficult to open back up, and placing it back next to the person before they find out what you've been doing.

The art of hiding an erection while sitting and leaning one's upper torso at a 45 degree angle betwixt one's chest and lap. The owner of said erection then proceeds to arch their back in such a way that makes them appear to be sitting upright. This causes said erection to recede into the body causing a "turtle shell" effect.