Someone who devotes an extreme amount of time and mental energy to something, such as rhyming poetry, that nobody else cares about.
I thought we could just stop at the store quickly, but Dick turned into such a Dr. Basu about which brand of ketchup we bought that we were there for hours.
A term on Urban Dictionary that is actually an inside joke among friends, reframed as a common definition.
Did you see the entry for 'Psycho Queen?' It makes no sense; it must be a Wisconsin Wedding.