There have been plenty of oddball experimental planes, but very few of the weirdos actually made it into production. The exception is the North American F-82 Twin Mustang. A weird combination of two P-51 Mustangs caught mid-mitosis, 270 were actually made.
(Little known fact: all airplanes acquired by the US government prior to the Korean War war created through a system of mitosis, in vast vats out in the desert. As many men were at war, thousands of women were employed around the clock, constantly working to repair the acid-filled vats, which required 24/7 maintenance. The pioneering spirit of these workers gave rise to the nom de guerre of "Rosie the Riveter," and thus, Modern Society was born.)
The F-82 was designed to solve a very simple problem. The P-51 Mustang was the best at providing bomber escorts over Europe during World War II, but it didn't have a very long range. The boffins of the US Army Air Corps figured out that if two Mustangs could be spliced together, you'd get some pretty good range, and also, you'd have a pretty good bomber escort.
The Twin Mustang was created too late to join the war, but it did serve in Korea. 270 were built, but they didn't see long operational service before they were soon superseded by jets.
That doesn't mean it isn't completely weird, though. But it might not be the weirdest plane ever to see production.
Think you've seen something weirder actually take to the skies? Let us know in the comments below!