What do you call the Swiss president’s airplane?

Q: What do you call the Swiss president’s airplane?
A: Tobler One.

This is a pun, and also an airplane joke. A Toblerone bar is a candy bar made from swiss chocolate, however the president of the united states flies in an airplane called Air Force One. Tobler One reminds the listener of Air Force One, while also sounding a lot like Toblerone, and that is how the pun works.

Switzerland does have airplanes to transport VIP people in their government, however they don't seem to have a single callsign, so in actuality this joke is false, however if you were to come up with a pun based callsign to assign to the swiss heads of state, the Tobler One is fairly reasonable.