The use of "extreme" in the name is partly supposed to convery the "in-your-face" attitude.

XP takes previous approches to software development and turns them around completely.

From the stories that I have heard of Kent Beck teaching people about XP, he's very extreme as well. Very entertaining stories. In a post grad course I took, we covered XP in one lecture. My lecturer took an extreme approach to teaching it, which made the lecture a lot of fun and carried across Kent's attitude. I've picked some of this up as well, so I don't talk about extreme programming, it's EXTREME Programming!