I've had some interesting discussions with my classes whether the example presented is classical, operant conditioning or a bit of both. Is Dwight being reinforced for putting out his hand when he hears the discriminatory stimulus of the computer OR is the computer sound a CS and putting out the hand a CR? And, what about the strange taste he has in his mouth at the end of the sequence?
For those of you looking to show the clip from the original DVD, you need to find the fifteenth episode of the third season entitled "Phyllis's Wedding". Below I have a number of websites which include the clip. If none of the sites work (I have found it hard to find a site which consistently includes the video due to copyright issues), do an internet video search for Pavlov, The Office, Prank, and/or Altoids.
These links are active as of December 15, 2009