How can i made it when you say "/e dance" that i throw my head or something?

Wat? Just wat? This is too hard for you, you basically need to check if the player chatted "/e dance", and while the player is doing the animation in the same time the player throws his head (also causing your death) and then ending the animation. But if you read carefully what I wrote, I said "in the same time the player throws his head", this means that you need your own dance animation and you can do something like this:

-- This is the code in the metalanguage
if the player chatted "/e dance" then
    stop current animation
    start your own animation
    throws his head
end