Any superstition is bizarre unless you happen to believe in it yourself, because the whole point of a superstition is that it isn't based on any reason or evidence. If you put 'most bizarre superstitions' in a search engine you will find several lists, quite different from each other because your definition of 'most bizarre' depends on you. But this list is quite interesting.

Superstitions tend to revolve around simple everyday things, like food, animals and objects we use every day (for instance, the belief that you shouldn't give someone a knife as a gift, but must always ask for a small payment for it. otherwise it will cut your friendship with the other person.) It's also interesting how superstitions vary between cultures; eg, a black cat is lucky in most of England, sometimes unlucky in the north and always unlucky in several other European countries.

My own favourite superstition, though, is the magpie rhyme.