Savaniscient
A combination of the words savant and omniscient; when someone knows a god-like amount of knowledge about a very a specific subject.
Martha: Most species of turtle have five toes on each limb, so a turtle could hypothetically give you a high five
Tyler: How and why do you know that?
John: The woman's savaniscient, she knows everything about turtles
Tyler: How and why do you know that?
John: The woman's savaniscient, she knows everything about turtles