Obviously it's a date of great significance to him, but why? It could be when a new single of his drops, or when he debuts some other new venture, but we're hoping he just revealed girlfriend Kim Kardashian's due date.
The reality star announced that she was pregnant in December, so that math would compute.
If the seemingly yet-unnamed Kimye baby does make his or her grand debut on June 18, he or she would share that birthdate with a few notables: country singer and Voice coach Blake Shelton, Beatles rocker Paul McCartney, the little boy from Where the Wild Things Are, and Barack Obama's late father!
It's also a historically significant day: Amelia Earhart became the first woman to fly over the Atlantic on that date in 1928, and Sally Ride became the first American woman in space on that date in 1983.
Maybe the baby has a future in breaking gender barriers in aviation?