How to silently remind guests to remove their shoes

re-post

1. Cast your eyes downwards at the guest's feet for a few seconds.

2. Make a faint smile with gritted teeth.

3. Look down at the guest's feet again.

4. When the guest looks down, nod.

This may not to work on first-time guests. This is best for reminding people who already know you don't want shoes in your house.