If only there were some way to determine what was meant. Barring that, maybe it's best not go around saying such things if you can't even convince one out of twelve people that you weren't serious.
Regardless of whether you truly intend to carry out the threat, the threat itself is a form of violence. It imposes your will on an unwilling subject.
If you rob a bank with an unloaded gun, you can't claim afterwards, "oh, they were perfectly safe and didn't actually have to give me the money, so therefore it wasn't a crime."