The one that made me laugh....
I came back from LAX with one of their freebie liquids bags with the airport logo printed on it. No trouble with it going through security at LAX, BFS, BHD, GLA, SFO, FRA and LHR - but the screeners at Gatwick threw a complete hissy fit - it wasnt regulation , wasnt legal and I needed to go back and get a plain one from the entry point to the queue.
No amount of arguing that the wee bag had probably travelled more miles than the staff had - they weren't having it - even though it was an official bag given out by a major airport......
Jobsworths - the lot of them!