When the French developed the bus, they immediately realized they need plenty of computers and even more software development for those computers. So they went to who else but good old Bill Gates. Well you know Bill when he develops an operating system he always puts in a back door and some form of gimmick. So he figured that he will program the computer to whistle "Yanky doodle comes to town" whenever the thing goes through a cloud.. .In fact if you press simultaneously PROG, OVERFLY and 6 on the MCDU you get the lyricks of "Yanky doodle" on the MCDU so you can sing along to the music.