The first Obfuscated C Code Contest, in 1984, allowed entries of up to 512 bytes. This one, from an author who asked to remain anonymous because of a well-known connection to the C language, prints "hello, world!" by defining its own function named read that actually writes.
Every piece of it is a joke about something true. The string literal "]<i;++i){--i;}" is indexed with the integer i instead of the other way round, which C permits because a[b] means *(a+b). The expression '-'-'-' is zero, so read is called with file descriptor 0, and '/'/'/' is one. The loop body advances through "hello, world!" one character per call. It is the first winner to be tattooed on someone: Thomas Scovell had it inked in 2005. The contest's own copy adds a cast or two so modern compilers accept it; this is the 1984 text. The contest it opened still runs, and for forty years it has been the museum where C programmers show each other what the language will tolerate.