I designed a crash proof airplane made out of rubber...

I designed a crash proof airplane made out of rubber.
It's called the Boing 747.

Here is another airplane joke. The joke here is also a pun centered around the word boing. A rubber airplane would probably bounce, and the word boing is an onomatopoeia for the sound that is made when something bounces. The word boing also sounds a lot like Boeing, which is a manufacturer of airplanes.