Something in your teeth
Have you ever been stuck in a position where someone is being very rude to you and you just do not know how to handle it? They are trying to put you down or insult you and all you want to do is stop this conversation before a conflict breaks out.
Try telling them that they have something stuck in their teeth while they are speaking to you. This will make them stop talking and usually check their teeth or even get up to leave in search of a mirror. Congratulations, you have bought yourself a moment of rest or a chance to escape.