One year for April Fools Day a bunch of us took a spare phone and reversed the numbers on the keypad so that 1-3 were on the bottom row and 7-9 were on the top row. We then waited until our boss was gone and quickly switched his phone with the "special" one. Then, one of us gave him the message that his wife had called. We all hung around just outside his cubicle and listened to him attempt to call his wife several times. He kept having to apologize to the same guy each time on the other end. I was laughing so hard I was crying. Finally, when I thought I might die from trying not to laugh too loudly, I went in and told him of the gag.