Don't you hate it when...?

Don't you hate it when people who think they know everything run their mouth. There is this one girl i my homeroom who is the most Negative Nancy I have ever met. She never has anything positive to say. She constantly has to complain about someone or something. Whenever she steps in the room I just feel this negative presence. Today she was going on about politics(like she knows everything) Saying how we went to Iraq for oil! And she wants her free oil! First off last time I checked we invaded Iraq due to them having weapons of m destruction. And how we lost the Vietnam war due to the Vietnamese army being high on heroine? I mean the things that leave her mouth amaze me. Do you ever just wish you can turn and tell a person to "STFU!" without being penalized?