"Moving day" is a term associated with anal sex. It originated when scores of girls lacking in upper body strength got their boyfriends to agree to lug their heavy furniture up/down multiple staircases during the course of a move. Riddled with guilt while watching their men sweat and grunt when they could be relaxing with a Corona and watching baseball, the girls decide to overturn the preexisting blanket ban on anal in the relationship.
Oh hey, have a seat!" "Sorry, I can't...today was moving day.