Japanese superstitions

My Japanese teacher brought me a list of superstitions today:

The number four:
It's considered inauspicious because it is pronounced the same way as the word for death (shi). Therefore, one should not make presents that consist of four pieces. In some hotels, and hospitals the room number four is skipped.

Give food chopstick to chopstick:
This is only done with bones of the cremated body at funerals.

Sleeping toward the North:
Do not sleep towards the North because bodies are laid down like that.

Funeral Car:
If a funeral car passes you, hide your thumbs! My sensei says that this is because your thumbs are considered your "parent" fingers. You need to hide your thumbs so your parents don't die soon.

Cut Nails at Night:
If you cut your nails at night, you will not be with your parents when they die.

Lie down after eating:
If you lie down immediately after eating, you will become a cow.

Whistle in the night:
If you whistle in the night, a snake will come to you.

A couple of other ones we talked about were:

Being alone in the room with a porcelain doll:
Apparently, their hair grows when you are alone with one.

Potted plants for someone in the hospital:
Thats like telling the person that you want them to grow roots in the hospital.