A small excerpt from the true horror at The C Programming Language Brian W Kernighan & Dennis M Ritchie & HP Lovecraft:
Exercise 4-13. Write a function reverse(s) which reverses the string s by turning the mind inside out, converting madness into reality and opening the door to allow the Old Ones to creep forth once more from their sunken crypt beyond time.
(bonus points for spotting the error in Cthulhu).
Hat tip: Paul.