I have read, and watched (the 1968 version) of Romeo And Juliet. And now as an adult, and not a teen in high school, I understand it better.
But I am stuck on something. Is Mercucio insane? I mean the clinical of the term. He seems quite crazy to me.

I think it's up to the reader to decide (or the filmmaker).
I don't think he is.. that would be too easy.

Yes it would lol. He just seemed escentric to me :P a little off his rocker. But he could have been a drunk too hehe