To cross one's fingers / Croiser les doigts

As touching wood, this expression is used in both French and English.

The cross is the main symbol of Christianity. So what better sign to use in order to keep evil spirits away and prevent a variety of misfortunes befall?

None.

Damned! Religion is really everywhere...

Boring...

Drown in a glass of water

During the past few weeks, I have used this expression twice or three times. Of course, nobody understood me.

From the French expression 'se noyer dans un verre d'eau', this is used when some people can be overtaken by minimal difficulties.. just like if they would be able to drown in a versy small amount of water.