Sagging pants: wearing pants below the waist so that undergarments are showing.
Most sources report that sagging pants began in the prison system. Belts are not allowed to be worn, due to the fact that they can be used as weapons or as a means to suicide. This resulted in the ill-fitting generic pants, too large to stay up on their own, to ride low on prisoner’s hips. Hip-hop artists adopted this look in the 90s (because you're not cool, if you don't do time, right?), and it quickly became popular among the youth.
Ironically, this PSA is threatening time in prison for sagging pants.
The most disturbing myth of the origin of saggy pants also comes from the prison system, and raises even more serious questions about why you'd want to emulate this trend. Sagging was said to be a symbol that the sagger was sexually available to other prisoners, or alternatively, already taken by another inmate. While several sources claim this to be true, others (like Snopes) tells us this is just a nasty rumor.
Sagging pants may also be as simple as a rebellion, claims another source. The stereotypical “nerd” wears his pants very high, sagging is the exact opposite.
Looking ridiculous (though inevitable) is not the only risk of sagging pants, it is linked to erectile dysfunction, hip problems, and lower back issues. "These issues stem from consistently wearing pants well below the buttocks, so low that one must change the way he walks." But hey, I'm sure the ladies you're attracting with your sweet look won't mind, right?