I haven't played any jokes today, but I have played some good ones in the past. One of my favorites was one I played on an ex-boyfriend who lived in another state. I went to my room, put on the newsradio station loudly so it sounded like there were lots of people around, called him up, and in my most frantic voice said "I'm at the airport! I've been here for a couple hours! Where are you? I thought you were going to come get me!" I had him convinced that I had come in for a visit and he forgot we arranged that. He was literally about to leave for the airport when I told him "April Fool!"
I played another good one on a former client at the paper a few years ago. It was a Friday and I talked to this guy, confirmed his ads and gave him prices like normal, then I said "By the way, today's my last day for a while. You'll be dealing with Carolyn for the next several weeks because I am going on maternity leave." I had just met with this client in December and it was obvious then that I was not pregnant, or if I was, I was nowhere near pregnant enough to be due in April. Still, he totally fell for it and was asking me if it was my first baby, if I knew the gender, what names I picked out, etc. I played along til I was about to lose it, then I finally said "By the way...what's today's date?"