A person who is a walking encyclopedia of questionable facts. Someone who is mostly believable, and knows several details of an idea, but misses context or has misplaced context. An intellectual grazer. Typically very attractive, and when wrong they still have their good looks.
Monty Python's Quest for the Holy Grail.
Bridgekeeper: "What is the airspeed velocity of an unladen swallow?"
King Arthur: What do you mean, an African or a European swallow?
The Bridgekeeper is a Wikipoopoo. Also guys named Jonathan.