This doesn't sound plausible as a joke. If you were going to do such an obscure joke, why choose Myth? Why not say "Gotcha" or make up an obviously fake cracking group name.

Number 3 is at least plausible, but anyone who could do this would have to also know that he'd be caught if someone read the binary. Now, if someone wanted to play a real practical joke, it would be to patch the compiler binary so that the compiler automatically inserts this binary watermark in whatever is compiled.