What is the drink at the front of a Thai restaurant?

Question

When I walk into a Thai restaurant, there is usually a drink on a shelf near the front door. What is it and what is it for?

Answer 1

Hmm... I'm not sure. My favorite Thai restaurant doesn't have anything like that.

EDIT - is it really necessary for the thumbs down people? It's true that my Thai place doesn't have this offering - that's not an opinion in any way, shape or form.

Answer 2

Thai people believe that everything has a spirit that resides and protect the people and the surrounding area.  The drink you see is the offering for that spirit similar to offerings for buddha and other entities.

Answer 3

I think it is for Buddha. Is the drink near a statue? It is an offering.