Where will you find diapers for teenagers?

http://www.xpmedical.com/

They have some of the best diapers you can get. I use the Abena Abri-Form Briefs for school.

Also if you wanted baby like diapers in teen sizes,

http://www.abuniverse.com/products/disposables.asp

Actually, those are rather great sites to check out. But you can also just find Goodnites pull-ups at any store.