Up, Up and Buffet!
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The restaurant's theme is providing a realistic experience of what it's like to eat during a flight on an airplane. For example, the "captain" announces that the plane is experiencing turbulence, and men outside push on the plane's wings with poles, tilting it from side to side. The silverware is kept in the luggage compartments, as Homer painfully discovers when "turbulence" makes the compartments' doors pop open.
The Simpsons ate at the Up, Up and Buffet! on Homer's and Marge's wedding anniversary. Homer and Marge had made plans to go to The Gilded Truffle, but when Grampa didn't show up to babysit, they ended up bringing the kids along and went to the Up, Up and Buffet! at their insistence. As the plane was shaken by "turbulence," Homer and Marge looked wistfully out the window at a young couple having a romantic dinner at The Gilded Truffle.
 Behind the Laughter
The restaurant's name is a pun on "Up, up and away!", one of Superman's old catchphrases.