A Traditional Microsoft "Welcome Back"
Microsoft has evolved some, um, unique traditions over the years. One of these is the “Welcome Back Carter” tradition. When a Microsoftie returns from an extended absence (honeymoon, maternity/paternity leave, trek across Siberia, etc) they find an office that is altered beyond recognition.

The sign on the door reads, “Do NOT enter, unless you are Carter. Carter, push hard to compress styrofoam.“ The window is filled with packing peanuts (as was an overhead box that dumped peanuts on Carter's head when he entered) and the walls, floor, ceiling, furiture, and windows are festooned with orange Microsoft cups.
Some office alterations are legendary, such as one where a team disappeared a teammate's door by walling it in (sheetrocked, spackled, and painted). Most, like the one pictured above, are fairly tame. I've seen wall-paper jobs, hundreds of hanging baby figurines, real furniture replaced by beach furniture and the floor covered with sand, and many other ingenious alterations, some of which the occupants actually retain.