That dubious distinction given to someone who has amassed a huge amount of knowledge, historical information, or worthless information and can provide said information on demand to fill in gaps, correct ignorance or just annoy others. Can have a lot of expertise and might be smart. He can easily provide information such as:
Almonds are members of the peach family.
A cat has 32 muscles in each ear.
It's impossible to sneeze with your eyes open.
Let's consult BergerPedia when he gets back from lecturing to settle the argument about which planet rotates the most around the sun.