If you ever want to mess with a deaf person who reads lips (and who among us hasn’t wanted to mess with a deaf person at one time or another?), go up to him or her and say “Vacuum!”
A lip reader can’t tell the difference between that and “Fuck you!”
Actually, you probably only want to do this with someone you know really well, so as to avoid unexpected consequences.
Actually, you probably shouldn't ever do this. Ever.