Lol if you want it reeeaaallllly super green, put the dye on, put a shower cap over it (one of those cheap plastic ones) and blow dry it on high heat (heat makes it process faster and more intensely)

You may have to do it a few times. And you'll want to make sure to use vaseline with that around your hair line or you'll have a green face for a week or so

Hahaha