I've worked in several places where "sagging"- the style of wearing your pants so they hang down around your lower butt thus exposing your underwear- has been a problem. In every school I've ever worked in it has been a strictly prohibited style of dress, likely because of concerns it's some sort of gang identifier (I've never known it be one...). I've always treated it like gum chewing. It's a minor offense, I ask the student to correct it, and go on with my day. There are enough challenges and misbehaviors that spending a great deal of time fighting sagging pants is, in my opinion, an unwise use of time. Hell, maybe if I'd stop eating pizza for dinner four nights a week my pants would sag a little.
Some teachers, I suppose just like the gum rule, are hard core on the sagging issue- particularly female teachers who in fairness, should not have to know whether their students wear boxers or briefs.
While working at an urban middle school, sagging was full on battle. Teachers regularly complained in faculty meetings about how huge a problem this was. Many teachers were upset that the dean of students would often take little action on referrals that teachers wrote for sagging. One teacher took matters into her own hands.
Beth Jones was an eighth grade social studies teacher who had more than a few screws loose. One particular student, Byron Washington, was a classic offender of the sagging rule. Byron came from a bad home, had zero motivation to learn, and didn't gave a damn about school. He was hoping someone would kick him out.
Ms. Jones yelled at him day after day about the pants thing, and was tired of her referrals on Byron resulting in little consequence. So one day, she called Byron to the front of the class and pulled out a brand new role of duck tape from her desk. In front of the class, she used the entire roll around his waste to hold his pants up. Byron, who in 8th grade was about 6'3'' with a full mustache, stood in front of his classmates crying hysterically and begging his teacher to stop. When she finished the roll, she sent him to the Dean's Office.
When Byron reached the Dean's Office he'd probably lost 5 pounds from all the tears and snot that flowed out of him. He was broken and totally humiliated. The dean immediately removed all the tape.
Around lunch when the dean and Ms. Jones got a chance to talk about things, it got very ugly and unprofessional. It's the only time I can recall seeing two adult educators (at school) screaming, "Fuck you!" "No, FUCK YOU!" at each other. The dean felt that in addition to being overly humiliating, taping his pants up was a borderline civil liberties violation as he couldn't use the bathroom (a entire roll of duck tape covers a lot ground...). To this day, I doubt either individual believes they handled that situation wrong.