Superstitions

In grade 5, we read something about superstitions. There were 5 superstitions. One was true, the others were made up. We also made up some superstitions.
Can you guess which is true, and which ones are made up? Only one is true.

1. Don't walk under a ladder, or you will get bad luck.
2. Don't dance under a ladder, or a hammer will fall on your head.
3. Don't swim near a shark, or you will become a shark's friend.
4. Don't use a wig to clean your house, or you will lose all your hair.

I think number four is the best. Do you agree? (请留言）