This is a true story. It happened to me. It's a prescriptivist's nightmare and a descriptivist's dream...

Teacher: I need to get more sleep. I'm mad tired.
Student: Miss, not to disrespect, but I hear all these people using "mad" wrong.
Teacher: Really? Like "mad tired"? I hear people say that a lot.
Student: Yeah, I know. But it be the wrong way to use it. It mean "a lot". You know, like "There was mad people in there."
Teacher: Oh, I see. Thanks!

;0)