A nightmare in which a person, specifically a nerdy person, forgets some of their nerdknowledge, such as a complicated math equation or a video game cheat.
Eddy dreamed that he forgot half the elements in the periodic table. What a nerdmare!
He proposed to his girlfriend in a Mario suite and jumped up to get the ring out of a question mark box. He's a nerd and she's a nerd. That is what we call a nerdmance, ladies and gentleman.