A lisp
The worst thing ever when you talk and it sounds like you're a brain-dead idiot.
I said 'snake' and it came out 'thnake' and everyone laughed at me.
He tried to say 'silly' and it came out 'thilly' and no one believed him.
She tried to say 'soda' and it came out 'thoda' and I called her a moron.