Block the signal on the TV remote with a tiny piece of black paper, or use a small piece of black electrical tape.
Prepare a special sandwich for the victim. But don't remove the wrapper from the slice of cheese. When they bite down the victim'll get a chewy surprise.
If you're a woman and have a boyfriend , this prank is for you! Put a pair of female panties & put them in your significant other's vehicle. During a drive, locate the underwear and create scene! After he gets upset, tell him 'April Fools!'
Find a small picture of a a funny creature (monkey, donkey, baboon, etc) and use a glue stick to place it over the photo on victim's driver's license. Then send him out for beer, or have some better excuse to send them somewhere where they need to show their ID.
Put a small amount of paint or ink on your finger. Go up to your victim and pretend to notice a "mark" on the victim's face. Tell the victim that you'll rub it off. Instead, actually place a mark ON their face. Act like you got the mark off and walk away.
Record the morning news telecast of the rainy day when schools were closed due to heavy downpour/snow. Then play it back on April 1st in the morning while the kids are getting ready for school.
Swap the phones of the victims who own similar makes and models but keep them in different color cases, giving each person back the correct case, but the wrong phone!
Try covering the urinal with a good quality cling film, tie it tightly so that its not visible at at a glance then wait to see who gets splashed first.
Block door with a see through plastic wrap. Then wait and watch who gets bounced back on opening the door.
Attach a rope to the back bumper of target's car and tie a collar in such a manner so that it drags on the ground. For more fun can try putting that collar around a stuffed animal. For a good dose of fun ride along and watch the funny reaction of other drivers on the road!