A biologist, mathematician, physicist, and computer scientist are all on safari in Africa when they suddenly see a spotted zebra running alongside the truck. They are all astonished and the biologist is the first to speak.
Biologist: Wow! What a find! Spotted zebras exist in nature.
Physicist: Actually to be more precise -- at least one spotted zebra exists.
Mathematician: Oh, but that is not even precise enough -- at least one side of one zebra is spotted.
Computer Scientist: <slapping his forehead> Oh, no! A special case!
Truck Driver: what have you been drinking? I didn't see no Spotted Zebra!