I have a friend with a twitch but he's never been diagnosed with Tourettes so I'm not sure really. I certainly don't know anyone who has it really bad.
One of my boyfriends used to have a physical tick, he'd do some twitching thing with his face.
I think someone could possibly fake it, but I don't understand why anyone would want to. Not that it's a bad and embarrassing thing, I just think it'd be disrespectful.
Then again, this is humanity.