So, uh, this isn't OK.
Look, I get that Miguel Britos is frustrated. The whole Napoli team was frustrated. He'd been tangling contentiously with Juventus' Alvaro Morata all match long. But you can't go around headbutting people. That's just not OK. There's no world in which that's OK, unless you're a professional fighter in-ring during an event in which headbutting is allowed. Guess what? Britos isn't that professional fighter. He's a footballer. And headbutting is so not OK in football.
The audacity he showed to protest his sending off was really something too. There was no doubt of what he did, or that it was worth a red. Just look at it in slow motion:
That's a solid hit. No grazing blow, Morata didn't fake it, nothing. Britos turned and smacked him right in the face with his forehead. Enjoy your three-match suspension, and likely longer ban once the disciplinary committee gets involved.