Past Nastification
(n.) The state or condition of one who has had sex with one's own grandmother in the 1950s, thus resulting in being one's own grandfather in the present/future. This condition may create genetic abnormalities.
Nibblonian: "It's a genetic abnormality which resulted when you went back in time and performed certain actions which made you your own grandfather." Fry: "I did do the nasty in the pasty!" Nibbler: "Verily. And that past nastification is what shields you from the brains. You are the last hope of the universe." Fry: "So, I really am important? How I feel when I'm drunk is correct?" Nibblonian 1: "Yes. Except the Dave Matthews Band doesn't rock."
By Pablo, King of the Spaniards