Tool

A tool is someone that is kind of arrogant and like a douche or an a-hole. It is not what these other definitions say. PInk uses the term in "So What", she's talking about her ex. Who is not a poser but a jerk, to her anyway.

Pink is talking about her ex in this song. He's not a "poser" hes a jerk, to her anyway.

I'm gonna show you tonight
I'm alright
I'm just fine
And you're a tool so
So what
I am a rock star
I got my rock moves
And I don't want you tonight