I saw this on the Penny Arcade forums, and it cracked me up.
Another down's syndrome story:I was at the theatres watching 300, and there was this chatty bitch blabbing away on her cell phone, pissing off everyone around. Here in Canada people aren't used to people doing that, and we all tend to be pretty polite and non-confrontational in general so nobody said anything at first. After a minute or so, a guy with down's told her to shut up, at which point she pulled the phone away, turned around and yelled up at him "shut up, you fucking retard" and then finished her call... nothing happened after that, except obviously she made an impression on the guy.
After the movie finished, as everyone's assembling on the stairs to leave the theatre, she was standing in the middle of the stairway facing sideways, talking with a friend. (I never understand why "friends" can't tell someone to stop being idiots, isn't it embarassing to them to be seen with these kinds of people?)
The Down's guy came down the steps, stopped a step or two above her and yelled out:
This!
Is!
Spartaaa!
And proceeds to lean back and kick her in the chest, causing her to fall down the steps backwards, screaming.