This is a newish Australian film about a family with an autistic (not asperger's) teenager.
I haven't seen it. It sounds a bit like There's something about Mary, but maybe not so gross.
http://www.imdb.com/title/tt0865297/
Edit: sorry, I thought I put this in the movies/tv section. That's where I meant to put it anyway.
Edit II: Thanks for moving it.