One who has/thinks they have a great deal of knowledge, but grossly overuses it.

Someone who, at a party, always finds people walking away from them muttering " What a loser. Doesn't he have anything better to do?" after quoting useless and/or inaccurate statistics to make him look more interesting.

A person that uses their knowledge/feigned knowledge to make someone feel inferior for no other reason than to feel intellectually superior.