knowledge bucket
Someone who is full of random pieces of knowledge. He/she knows many words and other random crap, and is constantly surpising people with everything he/she knows.
Bob: "Well, yes, actually the people of the 13th century liked to eat _______ because it was good for their __________. insert name is actually related to a famous person from the 13th century named insert name through his second cousin once removed."
Christina: "Wow, you're a knowledge bucket!"
Christina: "Wow, you're a knowledge bucket!"