noun; a state of mind where one experiences a pleasant glow due to a combination of reminiscences of a past time, and completely forgetting how rubbish that time was whilst you were originally experiencing it.
Nostalgic Amnesia had set in, and Frodo found himself pining for the glory days in Mordor.
A play on words- similar to the word "nostalgic", only used in a negative sense to recall an event that traumatized you.
Every time I hear The Jonas Brothers, I get a little nastalgic because my ex-girlfriend broke up with me because I called Joe Jonas gay after seeing him dance the "Single Ladies" dance on Youtube. The Joehoez get me again. Blast!