Seemingly wrapped Dwight's chair, desk and everything on it in wrapping paper

In the Season 5 episode, "Moroccan Christmas," Jim wraps Dwight's desk with wrapping paper. Although, Dwight believes that Jim really wrapped his whole desk, Jim just wrapped pieces of cardboard to replicate his desk. When Dwight sits in his chair he falls down onto the floor, shocked, and Phyllis can be seen smiling.

Trivia

 * According to a Q & A at OfficeTally, the wrapping paper was wrapped around foam.
 * According to a Q & A, Justin Spitzer said that the prank that came up most in offices was wrapping someone's desk with wrapping paper.

Episode In

 * Moroccan Christmas