This video shows why, if you want to own a gun, you really need to have serious training in gun usage and safety if you are to avoid harming yourself and others. The video is designed to evoke laughter but the consequences of unskilled usage can be tragic.
Gun owners would also benefit from some basic lessons in physics, such as the law of conservation of momentum. Even though a bullet is small (around 5 grams), it can be fired with a muzzle velocity of 1,000 meters-per-second (not uncommon for modern high powered guns) and thus goes forward with a momentum of 5000 gram-meters-per-second, and the law demands that there must be an equal momentum in the opposite direction and the shooter has to absorb it.
To get a sense of how big the recoil is, it is equivalent to being hit with a basketball (about 500 grams) traveling at a speed of 10 meters-per-second (roughly 20 mph) or a baseball (about 150 grams) traveling at speed of about 35 meters per second (about 80 mph) which is similar to fastball thrown by a major league pitcher. Both can knock you over backwards if you are not braced and ready for it.
Experienced gun owners know to fire from a prone position or if they have to stand, either embed the rifle butt firmly into the shoulder or, if firing a pistol, brace their arms and their legs so as to spread that momentum over the entire body to minimize the speed of recoil.