hehehe yeah thats a fun stage!!!

No matter what we did stopped him from doing it - distraction, holding his head gently, trying to not make him tantrum - nothing worked.

I think he stopped doing it when he banged his head on the bathroom tiles so hard he had a bump on his noggin.

funnily enough - he doesn't do it that often anymore!!

No advice - but wanted to reassure you that it will pass.