I mean I can disprove the flat earth theory by walking around the world, orbiting around the earth in space, or use something that relies on that, like say GPS. Whether Green Day is punk or not is a matter of peoples opinions. We can discuss what punk meant in the 70s, what it means today, whether its still relevant, how Green Day fits into that, it's pretty much someone's opinion whether they classify them as Punk.

Apparently The Monkees were also written up in Punk, are we calling them punk now?