A small refrigerator and shelf with VERY expensive food and beverages in it. It is not really an Honor Bar. You consume and each day they refill it and charge you. (Honor kind of indicates you would just tell them!)
There is one other possibility. The Courtyard I stayed at last night had an Honor bar in the lobby, you took your drink and signed a sheet indicating what you had. Of course it was directly in front of the check in desk to make sure you were honest.