Rear-Dee-Dear Share definition Flag A popular expression from 1970 upstate New York. It means, "You're lying," or "I doubt what you're saying is true." Eli: I'm taking Megan Fox to the movies tonight.Joe: Rear-Dee-Dear!!!! Rear-Dee-Dear by Ehrenpreis November 1, 2010 0 0 Get merch Get the Rear-Dee-Dear mug. Buy Now — $32.95 See more merch