What I've never understood about pineapple or anchovy is how much people seem to give a **** about whether or not someone else does it.
I mean, mayo on a pb and j sounds as disgusting as can be to me, or if somebody liked banana in their gumbo I wouldn't want a taste, but if some people want to do it I'd let them knock themselves out, it wouldn't get me all worked up. I know we're mostly joking around, but some people do seem to get legitimately riled up about pineapple or anchovy on other people's pizza.
(Oh, and before someone brings it up on the other half of a pizza being shared isn't the same as just getting mad about a guy down the hall or the idea that someone somewhere is doing it. I'm talking about people that seriously get mad about it being done by unrelated people.)