INTERCAL

Two Princeton students wrote it overnight in 1972 as a parody of the language-design arguments of the day. The full name is "Compiler Language With No Pronounceable Acronym", which is itself a contradiction. Programs are required to be polite: statements should be prefixed with PLEASE, but do it too rarely and the compiler rejects the program as insufficiently polite, too often and it is rejected as excessively polite. The acceptable ratio sits somewhere in between and is not consistently enforced.

The operators are named interleave and select, and do bit manipulation in ways that are difficult to justify. Eric S. Raymond wrote C-INTERCAL in 1990 and added COMEFROM — GOTO's mirror image, where the jump is declared at the destination rather than the origin. The joke aged into a genre: the whole family of esoteric languages traces back here.