Club 33 is in Disneyland's New Orleans Square, near Pirates of the Caribbean, and was created as a secret venue for Walt Disney to entertain celebrities and investors.
In addition to serving breakfast and dinner, it is the only place in Disneyland that serves alcohol.
Entry is restricted to members, and membership has a 14 year wait list and a $25k fee.
However, if you book a tour called Backstage Magic with Disney, you can unofficially go there for breakfast as part of the tour (as long as an event isn't happening there). The tour is several thousand dollars, but there are many other interesting perks, and it's a worthwhile experience.