Shit-arser

A situation where yourself,or another person causes temporary frustration & anger,time wasting and an increased desire to blaspheme.
e.g When somebody nips into a parking space that you have been patiently waiting for for more than five minutes.

Diane: Hey Ginny! that guy is now going to reverse out of that space,lets wait.
Sam: Well spotted Miss D! You are so cool!

(5 minutes later)
Ginny:NO WAY LOOK! There's snaggletooth! nipping in to the space we have been waiting for! What a SHIT-ARSER!!

All three: She should know bettda!!(look it up)