I have no idea why my head started doing it, but even tho im not superstitious after I heard about knocking on wood to not jinx something I HAVE to do it.
Its been around 4 years since it started, whenever I'd think something (e.g how I've never smashed my phone before) I have to knock on wood, if theres no wood around or im around others I lightly knock my thigh. I've been doing this several times a day for years (hell just typing this out I've already had to knock over 10 times)
Usually the second I think of one thought I really don't want it to happen, after I knock on wood to "un jinx" it I start thinking of a million more things I don't want to jinx, I can't stop myself. I feel if I were able to make a compilation it'd easily be over an hour long within a week