Three surgeons are washing up in the Surgeons' Lounge one evening, when they start discussing their favourite patients.
The first surgeon says, "I like operating on Germans." The others ask why. He says, "They're wonderful... You open them up, and everything is exactly as in the schematic. There's no guess work."
The second says he enjoys operating on Japanese. The others ask why. "You open them up, and everything is colour coded. It's that simple."
The third says he enjoys operating on politicians. The others ask why. "It's amazing -- you open them up and find only two moving parts: a mouth an an a*sehole... and they're interchangeable!"