You can create a listing in the Everything Else category. This is what I would do-
Don't include the upc, replace with a different number instead so it won't be matched later if someone lists it into a differing category. And so you look like you are trying to do it right in case there's a problem
Ensure the picture of the item is appropriate so children are not exposed to X rated material when surfing Amazon. No need to show anything offense, no one cares what the doll looks like anyhow.
The only objection I would think would be the picture and description of the item. Just keep the wording being something if a child read it, they wouldn't really understand what you are talking about.
Try to use other wording than Blow up Doll. If my child was surfing and ran across something like that, and he/she asked me what a blow up doll was, there's a chance I would call Amazon and complain about the listing.
If there's another slang term for Blow up doll that is not vulgar, then I would try to use that. Then add the manufacturer to the title? What would be even better is to get ahold of some vintage blow up dolls, then you would be in teh clear listing it in Everything Else because that's the only category that doesn't require UPC Codes. Also if you have something for free to give them with the order, I'd go that route. Your customers are going to be scumbags, drunks, mentally ill people etc...who are probably likely to raise heck.
For whatever it's worth... a penny...or less... who knows.... Good luck   | 
