I’ll start:
Flags fluttering or anything particularly flappy, which made coronation weekend a bit of a trial and makes me nervous about going camping…
inanimate things that look like animals or people - there is a house nearby with very large, baffling, pair of stone Great Danes outside, which shall not be passed under any circumstances.
Tinfoil, sellotape and Velcro (being pulled off the roll/ pulled apart)
Helium balloons - not to be trusted.