I enjoy watching pranks being pulled on people. I am usually not creative enough to think of ones of my own. However, I eagerly join the bandwagon if one is going on. The tv show, The Office, has had some great jokes: calculators in jello, cell phone put in the ceiling rafters, desk put in the men's room.
At a previous job, a co-worker set out some jelly beans for people to eat. We didn't tell anybody that they were bertie-bots. (jelly belly's prank jelly beans) flavors were: puke, boogers, hot peppers. Another co-worker came up and took a handful of the jelly beans. We couldn't go through with it. We had to tell the co-worker they were prank jelly beans.
In college, I took a picture of my roommate on the toilet. And then put it on the bulletin board in the dorm lobby. That is my extent of pranks. I was actually mad at her because she did something to me. I too k the picture in the first place because she always left the door open, and I thought that might teach her.