One who loves the sound of their own voice so much they have convinced themselves they actually know what they are talking about. They often take jobs which will allow them to talk and give them a captured audience, such as a Psychology teacher.
Dr. Nicodemus is such a pompous windbag. We could have learned everything he spent an hour talking about in five minutes. He sure does love the sound of his own voice.
"Pompous Pep," otherwise known as "Endangered Species," is a euphemism for the Vlad/Danny slash ships in the Danny Phantom fandom. Most ships have code names of this sort (Skulker/Danny is Callous Quarry; Walker/Danny is Jail Bait; Clockwork/Dan is Meddling Minutes) so as to make searching for stories with that pairing easier for fans.
For example, a lot of stories might have the words "Vlad" and "Danny" in the description, but more often than not those are father/son fics. Likewise, Skulker is always chasing Danny, and Dan is hardly ever seen without Clockwork right behind him. This is just a simple mechanism the fans created to simplify searching for their favorite pairings, though most fans would like to viciously strangle whoever came up with the sometimes less-than-appealing names.
Girl 1: I was reading some Pompous Pep the other day, and it was so cute! And Danny was TOTALLY trying to molest Vlad, and... o3o
Girl 2: Stop. Just stop. -__-
Girl 1: T^T