When somebody erroneously states that something is the best or worst thing ever because they have only just encountered it and are too confused by thier unfamiliarity to it to realise its true quality.
Sam:"I got this CD yesterday, its the best album ever!"
Tom:"I think in a few days you'll realise you were just suffering from novelty blindness."
The man or woman who routinely steamrolls their way into a private conversation and makes it their own, usually stealing one conversation partner and leaving the other feeling jilted.
Common incident in staff rooms, classrooms, etc., where interesting conversations are few and far between.
Esmeralda: "Oh you're so funny Rufus, I would be so unhappy without you to talk to."
Rufus: "So I was wondering, well if you're not too busy tonight, maybe we could-"
Jean-Claude: (pokes Esmerelda) "Traffic was bad this morning..."
Rufus:(looking totally cast aside)"That fucking Jean-Claude... what a conversation thief!"