Photo Credit: halloweeparty13.com
When I asked a friend the most offensive Halloween costumes, without even the slightest hesitation, she mentioned the "Anna Rexia," costume she'd seen on a girl in a bar a few years ago. I thought she was either kidding or confused, until she sent me a link.
The "Anna Rexia" costume (Get it?), is high up on the offensive scale, because there's a company that actually makes it, markets it, then sells it, as if eating disorders are no big thing. At least you're not going to find a Trayvon Martin costume at your local Halloween store, or at least I would hope not, but I can't say I'd be totally surprised if one was made available for purchase.
Although there's a petition on change.org, to stop further production of the anorexia mocking costume, it doesn't seem to have resulted in any positive change as of yet.