Back in the 80s, writing 6502 with some other peeps one of the fun windups was when someone was away from their desk was to slip a SED instruction into their so

Back in the 80s, writing 6502 with some other peeps one of the fun windups was when someone was away from their desk was to slip a SED instruction into their source in an obscure function that wasn't called that often. If you get it right, they spend quite some time trying to track down why their code is misbehaving. A bit of misdirection (e.g 'oh, that target machine was giving problems yesterday, maybe the hardware is failing') can really help :)