Here are some favorite April fool's pranks that are safe, and most likely acceptable for anyone without causing harm or too much trouble even at work or school.
Prank Word Scramble from April Fool Zone:
This word scramble has letters that will drive your prank victim nuts. The letters for every single line can not be arranged into a word. This is especially great for a friend or co-worker that routinely does puzzle games! When they look at the bottom key for the answers they will then find out they were pranked.
Missing Shoe from April Fool Zone:
This works especially well for a significant other or child that you live with. The night before, when they aren't paying attention, grab one of every shoe they own. The next day when they go to get dressed for the day, they won't be able to find a complete pair of shoes.
At work, make a very close duplicate of a business card of your prank victim and make a typo in their name or job title. They will think they have been handing out business cards with the wrong information to everyone when you point it out to them!
This is a favorite that you can't do often-but either in the shower or by a sink that is sure to be used, take a bar of soap and coat entirely with clear fingernail polish. Allow it to dry. When someone tries to use it they will not be able to make it lather up!
If taking a shower without lathering soap weren't enough, here is another chance to get nice and clean...You put a rubber band around your spray nozzle in the kitchen sink. When the next person goes to turn on the water they are going to get sprayed!