A well-known British graffiti artist snuck one of his own works into the Tate Britain museum this week, and glued it to the wall, along with a typical title card describing the work. “The picture consisted of a rural scene with an image of police tape stencilled on to it,” and the card explained that the artist “argues that ruining the work in this way reflects how our nation has been vandalised by an obsession with crime and paedophilia.” No one at the Tate noticed the unscheduled addition to its collection until the painting came unglued and crashed to the floor several hours later.