Paint their nails while they sleep (and hide the polish remover).
If you have a spray nozzle on the kitchen sink... put a rubber band around it in the morning before school so that when they turn on the water they get soaked.
Hide a walkie talkie in their room and from another room in the house......whisper things to him.... like sssssh ssssssh sssssh haaaaaaa haaaaa haaaaa. That should do it!
Yes... I had an older brother. That is how I know these things.
just like twiddlemuffins, you can take out the hose that fills up the toilet, out of the toilet and point the end at whoever is in front of the toilet. then when they flush, surprise. another one is undoing both sides of the cereal box, pouring the cereal into the box (instead of the bag) while holding the bottom together , and carefully positioning it up high.
The best element is the element of surprise! I sneak up on my brother when he's watching tv in the living room and i come from behind, wait a few minutes until everything is still and he's not paying attention then i jump out and yell some mumbo jumbo and scare the heck out of him! It never gets old :)
Put makeup on them while they're sleeping. Before they leave for school (if they go to school), stick a period pad on the back of their shirts; without them knowing. It would be even funnier if you put some kind of red liquid on the pad :P
I made my bro think I was bn nice by gettin him breakfast, and the night b4 I had put a bowl of cereal with milk in the freezer and gave it to hime in the morning
Put sammich wrap on the toilet seat. Did that to my cousin. LOLOLOLOLOLOL