Head on over to the UnMario Wikia. Be sure to register an account if you haven't already.

From Unmariowiki

An author's depiction of the worst plane ever.

another horrible plane

'Shroom Airport is the worst airport in the world. Only 4% or the planes flown by it have even made it. The worst thing about it is its design; a mushroom. I mean what kind of plane is shaped like a mushroom? Idiots have recommended to change it but the boss of the airport is none other than the retarded Bowser.

The 'Shroom Airport was almost given involvement in the Yoshi's Island Scandal (thanks to a plan cooked up by Ronald McDonald), but the ideas involving it were scrapped and Ronald was ground into cheese. Some also say that the mushroom-shaped airplanes of the 'Shroom Airport were the inspiration for the Titanic, Mario's kangaroo-shaped jet from Super Mario: Just Click Your Browser's Back Button.