People who press BOTH the call buttons on lifts. "I want to go up, thus the sensible conclusion would be to press both the up and down call buttons so that I inconvenience as many people as possible and add a great inefficiency into the system. Once the first lift arrives, which will undoubtedly be the one which is travelling in the down direction, I shall then embark and press for the floor above regardless then travel all the way down and all the way back up to the top."
Damn that really ****** me off.