On April 23rd, 2011, the Doctor Who episode “The Impossible Astronaut” premiered, starting off series 6 with some mind-blowing plot twists and some new monsters, the Silence. The Silence are creatures that you can’t remember seeing the second you look away from them. To combat this unusual type of warfare, The Doctor, Amy, Rory, and River draw tally marks on their skin to remind them that they’ve had an encounter.
To celebrate the day, Whovians drew tally marks on their arms (some even drew on their face) and went about their normal day, pretending like they didn’t know where the tally marks came from. Basically, Whovians love having inside jokes that freak people out.