Bunuel has a field day poking fun at social manners and mores. You'll have fun, too. These people just want to have a bite to eat. Is that so difficult? Yes, wonderfully so.
It seems to make no sense, but after you've watched it, many of its pieces stick with you and take on meaning. This is the movie where all of the elements coalesced for Bunuel: budget, cast, mood and feel.