In my day it was always the pilots that were regarded as thick-
Just in case anyone hasn't heard this one. During Confrontation in the 60s a Javelin nav ejects over Borneo and lands in the jungle (luckily in a clearing). Follows a path to the nearest village, on the outskirts of which is a food stall. A sign on the stall reads "Navigators' brains, ten coconuts a pound - pilots' brains 50 coconuts a pound. Indignantly the nav asks the bloke behind the stall why pilots' brains are so much more expensive. Unusually for a cannibal the bloke speaks English, and replies "Have you any idea how many pilots you have to catch to get a pound of brains?"