What does it mean to put three nails under the bed?

1. When you were making the bed, you didn’t even notice the scattered nails on the bed board;

2. The nails fixing the bed board moved and fell off, and there happened to be paper. Next;

3. Are there any pranksters in the dormitory? If so, I don’t need to tell you;

4. Are there any superstitious classmates in the dormitory? If so, it might be some kind of superstitious activity.

However, no matter what the reason is, as long as it doesn’t hurt yourself, it’s useless to overthink it.