I've been coaching the younger kids more often lately, but I still coach some high school kids.
Good luck What I do is get a rope or a belt and put it through the leg holes in your underwear.
Give the victim a normal wedgie and pull it high enough so that the leg holes are just below armpit level and underneath the shirt.
Once the underwear is done freezing the victim is wedgied in them until they thaw out.
After you have had enough, either jump off the high area, or ask for help.
The more they kick the worse the wedgie gets.