Complex sentence: While a wedgie can happen naturally, through underwear riding up due to tight garments or physical activity, wedgies are probably best known as a prank or as a form of bullying, where the underwear is forcibly pulled up by a second person.
Split into simpler sentences: While a wedgie can be created naturally, the term is usually associated with a prank or as a form of bullying. When a person is on the receiving end of a wedgie, their underwear is forcibly pulled up by a second person.