Aitsu, koitsu, soitsu...
 

Just a quick question about these words. I know they are considered vulgar and rude and definitely shouldn't use with your superiors, etc... and they should only be used causally among your friends. But,

1) Do girls use them too? If so, are they just boyish girls or maybe girls only use them when they are mad about someone?
2) And if someone is irritating them, they will definitely use aitsu, right? Instead of using ano hito or something like that.

Basically yes and yes, but there are no definitelys. Many people never use those words.

I agree with MMM. My friends at school only use it when they're joking around. I have seen it used on TV and video games in a provoking way, but not in real life so far.

Here's a new Japanese proverb:

あいつもそいつもどいつもこいつもドイツへ行く・・・ ・ :)