In one of his standup specials, Aziz Ansari tells a very funny story about an encounter with 50 Cent, in which he discovered that 50 Cent had no idea what a grapefruit was and refused to believe that a grapefruit is a completely different thing than the fruit commonly known as a grape. In this similarly amusing video, Penguin Patton Oswalt discovers that Batman's "one rule" is taken so far, that he actually doesn't know what death is.
The discovery and subsequent explanation should remind you of the moment your friend didn't know what some obvious fact of life was, and how AWESOME it was to discover his cluelessness. A great moment everyone should have.
[H/T: Clip Nation]