‎"In college, before video games, we would amuse ourselves by posing programming exercises. One of the favorites was to write the shortest self-reproducing program. Since this is an exercise divorced from reality, the usual vehicle was FORTRAN. Actually, FORTRAN was the language of choice for the same reason that three-legged races are popular." - Ken Thompson

I got the quote from http://cm.bell-labs.com/who/ken/trust.html . You should read the rest of the speech too, it's pretty mind-blowing.