I was thinking about this because my sister in law posted one of those "can you find the sniper" pics on her facebook page and I said the first one was easy, but the second one took awhile to find. There is only one, but I like the idea of someone pouring over every pixel of the screen trying to find a "second" one.
Once, while working at a pizza joint, I took a delivery driver's soda and replaced it with peppercini juice. Then to make things a little more entertaining, I put some more juice in a styrofoam cup... when he drank a sip of the bottle, I told him I put it in the cup...when he took a drink from that I gave him another cup with his actual soda in it. He dumped it out without trying it...can you imagine.
So, this year, I plan on bringing hot pepper flakes in to make my work's morning coffee a little spicy.
Anyone else have any plans or prank ideas they want to share?