For those who really want to know, the joint belonged to two of the worker’s from Vance Refrigeration. They smoked it on their way into the building and then said, “Oh, we should get a pizza.”
Actually, these guys are in the deleted scenes from a few of the different episodes. But, I don’t ever remember seeing them on the show. (To be honest, I can see why. Their scenes aren’t that funny.)
Update: They are the ones that dropped the bear off to Phyllis. Also, it seems that they maybe involved behind the scenes of THe Office beause they were there to receive the Emmy’s with the rest of the cast.
Here are two pictures. One from the Joint scene, and one when they are hitting on Pam for Valentine’s day.