The Zit
During production on Ewoks and Droids we would often burn off excess energy and frustration in a variety of different ways. We'd play practical jokes on each other... there was this one time when one of the layout artists mistakenly let us know that his mother and sisters were visiting the studio to see where it was that he worked. As soon as he left the room to go and meet them in the foyer, about 15 of us grabbed everything that belonged to him, including his desk and everything he had pinned up on the walls, chair, side table... everything and stuck it out on the roof of the studio (this took about 3 minutes). We then went about our normal business, drawing and such. In he walks with his family, proudly pointing out that this is the layout department where we produce cartoon shows. He comes around the corner and says with a wave of his arm, "And this is where I work..."
Of course there is nothing there but a big empty space. He stopped in mid wave with this great look of astonishment and his family looking very bewildered. I walked up to him and very officially asked him if I could help him find his way someplace. I then looked at his mother and sisters then looked at him and said, "Sir, if you're a visitor, you'll need to have a security pass and an escort."
Everyone else was busting their guts behind their desks. The look on his face was priceless. His family were equally as dumbfounded.
Another thing we would do is play table top hockey tournaments during our lunch breaks. We had some extremely heated battles.
To ease some of our frustrations we would also draw cartoons of each other doing an assortment of goofy things or pictures of the cartoon characters being mutilated in some horrific way.
He totally freaked out, grabbing all his photocopies and covering his head then running away yelling, "AAAAAHH!! Leave me alone!! Leave me alone!!!"
I just stood there for a few moments and then went back to my desk. Inspiration had struck me right between the eyes. I started drawing a three page comic about a guy who has a pimple on his ear... actually, you can just read it for yourself. The very first Zit.