Does it hurt if you get hit by a paintball?

We would compare it best to someone snapping you with a towel.

Only if you have on light clothing and even then it is a minor sting that lasts for 30 seconds. They offer protective equipment there if you are worried. You would be fine wearing a sweat shirt and blue jeans though.

Wear a long sleeve shirt or hoodie my forearm got hit good and left a scar

As long as you don't get shot in the nipple or the balls it will be fine