I would not press the button. I'd put it away in some safe place.
I'd take it apart to see how it works
Keep pressing it as an answer to overpopulation
Be very scared of it, and stand guard to make sure nobody tries anything. Possibly try to smash it to pieces.
I'd ignore it as some lame joke... or possibly laugh at it.
I don't know how many, how many times can a button be pressed in two hours?
It's obviously just a gameshow trick. Keep pressing it as long as possible, because you'll be rich and there's no way that a box with button can kill anyone.
I'd press it two or three times.
I'd press it 40 times, so I'd have a million dollars.