- "Ignorance" redirects here. You may be looking for General Ignorance.
"Nobody Knows" was the joker card used in the I Series; it was often described by Fry as a celebration of ignorance. Contestants were given a square card which had a white question mark on a purple background; if they correctly used the card, the screens would also show this logo. They were told to use the card if they thought the answer to a question was "nobody knows". Points were gained for correct uses of the card, but lost if the question had a known answer.
"Incomprehensible" had three "nobody knows" answers; "Imbroglio" and "Invertebrates" had two. "Inequality and Injustice" and "The Immortal Bard" had none (at least, no "nobody knows" answers made it through to the final cut of the XL versions). "Inequality and Injustice" was the first time an episode in a series with a joker didn't contain a joker question (unless "Elephant" is included).