When someone cced into an email, like a party invite, or a forward with many addresses in the cc list, uses the occasion to air there mostly pointless views to everyone in the cc list. This is sometimes done to make a point against forgetting to use the bcc option, but is often totally gratuitous.
All right anons! Spambully is in the house!
I'm sorry I don't know anything about the party - ever since the spambully hit it, I've been deleting the mails before I even open them.
Don't reply to the spambully or you'll become a part of his spam gang and just add to the general annoyance of everyone on the list.