Here is a bit of inspiration for some "foolish" fun...
This party table is full of gags just waiting to be discovered. The best part is that most of this stuff can be found at the Dollar Store, so lots of festive for very little cash!! You, of course, HAVE to start with Whoopee Cushions in the seats. Probably not well hidden enough for your guests to fall for it, but a great favor for them to take home and try on their own unsuspecting friends.
The cup full of mini-M&Ms on each plate not only matched the polka dots on the centerpiece, but also contained it's own surprise. To eat dinner, the cup needed to be moved out of the way, but guests had no idea that each cup was missing it's bottom!! Once picked up, the candy spilled out onto the plate.
For added fun, the little cup had a water squirting ring on top, and a fake lottery ticket attached. I wrapped the tix in colored paper and wrote "Good Luck" on each, but this would also be a great place to write names and double them as place cards. It is attached to the cup simply with a colored paper clip.
Under each place setting was a colorful maze placemat. I copied mazes from the internet, but for this particular theme, I took a thin black permanent marker and made an extra line towards the end, blocking the path to the exit. If you are careful, it isn't obvious at all, and then there is NO WAY OUT!! This should keep your guests busy for a little while. It said "Answer on back" in the corner, but when it's turned over, it just says "There is no escape... HA-HA-HA!! April Fool!!"
A classic gag is switching out the salt and sugar, so how could I resist? I filled one shaker with each, then added the question mark to make them wonder.
A couple of other things that I added were odd-flavored Jellie Bellies, and fake spilled wine, which I made pretty easily with nail polish and a plastic cup. As an added bit of decor, I found a great quote, printed it out, and framed it for the table.