You might think that playing pranks is just for kids, but why should they get all the fun? If you're a child at heart, then you should embrace that and learn some fun and harmless pranks to play on your kids. Fun and harmless is the key here, as you don't want to go traumatizing those sprogs of yours for life! Depending on how likely your children are to get annoyed by you playing a prank on them, you might want to have some treats on hand to negate potential tantrums. Although these would make excellent April Fool's Day pranks to play on your kids, there's no reason why you have to wait until then! Check them out and then get pranking!
After dinner, announce it's time for second dinner. Your kids will think you're mad until they realize you've made dessert spaghetti and meatballs.
Have a teen who has just got their license? A fake parking ticket might scare them straight. 
Put string inside mustard and ketchup containers for a silly dinnertime prank. 
Put your kid's sandwich inside one of these mold bags.
Put a toy in the mailbox for a shocking surprise.
Be prepared for tantrums if you give your kid one of these broccoli pops.
Put a line of stuffed toys outside the bathroom in the morning and watch your child laugh at the "queue" to get in.
Make some undrinkable juice (aka jello).
Try something like this for a bewildering ride to school.
Put worms in your kid's apple. Gummy worms, that is!
Make your child a grilled cheese, and watch their face as the realize it's actually pound cake sandwiched with butter cream.
Put googly eyes on everything in the fridge.
Make some faux ice cubes for some silly fun.
Give your kid some "doughnut seeds" (cheerios) to plant!
Announce you're having cupcakes for dinner. They might not realize they're savory until the first bite!
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