A third (fourth,... ect.) boob that cannot even lactate that exists just for fun.
Or
A humorous insult used to describe a bumbling idiot with a big smile on his face.
someone who insists that global warming is a hoax. (Whether we are causing it or not, it's still there.)
You may call that person an incompetent boob.
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi