If you haven't been there before, CafePress.com is an e-commerce web site where you can upload your own artwork and it's printed on demand on t-shirts, mugs, bumper stickers, pins and more. Disability topics cover everythings from autism to epilepsy to rare syndromes. Search for the term "wheelchair" and you'll see some pretty racy slogans created by and for wheelchair users. MANY NOT FOR KIDS!
While you're there, check out my Say it with Symbols Gift Shop at CafePress. You'll find appreciation gifts for teachers and therapists as well as awareness-building t-shirts for children and families who communicate with picture symbols. Certainly less racy than some topics, but the message is equally as important.