stands for Pain In The Ass. It is a way to describe people without them knowing you are talking about them. Used alot in the Medical field when people are constantly wanting your attention and pressing their call light for no reason.
Tellie- Man, Mr Robinson is getting on my nerves!
Amy- How so?
Tellie- He wants all my attention and won't leave the call light alone!
Amy- Wow! He's a P.I.T.A.