The worst feeling is when you are in a programmer team environment and after you start with the "Who the heck wrote this?!' rant, you realize... "Um, uh... yeah, I think that's some of my code. Never mind." Whoops.
I think it is poor form to potentially encourage someone to run a malicious and extremely damaging command, even if you do so in jest (yes, I see the smilie). Perhaps I'm overreacting, but my opinion can be summed up with the announcement at this link: