Re: The worst customers...
Had that experience at the airport. One guy tried to cut the line at the security check lane, it was 1) the priority lane already and 2) not very busy. He was sent back by security, then complained that he was traveling on behalf of (bigger airline). Still: no, wait your turn. The guy in front of me (former moderately highly ranked politician, who had patiently waited) told the security guards that "he won't be getting much older, if you stress that much and have such an over-inflated ego you'll get a cardiac or something really early". Smiles all around.
When it was my turn, the guard asked whether I had recognized him. When I said no he told me who it was and that "he is flying really regularly, really nice guy, always friendly and smiling". Made my day - And that of the people at the security control...