Ob- Obfuscated C Contest obi-wan error Objectionable-C obscure octal forty off the trolley off-by-one error offline ogg old fart Old Testament one-banana problem one-line fix one-liner wars ooblick op open Open DeathTrap open switch operating system optical diff optical grep optimism Orange Book oriental food orphan orphaned i-node orthogonal OS OS/2 OSU OTOH out-of-band overflow bit overflow pdl overrun overrun screw