The one that gets me is "it always happens in threes" and the lengths people will go to "prove this". I know a few people who get really annoyed when you point out the fact that other than when a group of three people are killed by a bomb or something simultaneously, most things happen one at a time. I have an ex that used to always wait until a third celebrity had died to bring out the "it happens in threes" and get highly offended if you pointed out some provable fact like she missed a celebrity that also died during that period , making it four.