Announce about the engagement of your friend on Facebook and tag him!
Superglue some coins to the sidewalk or any spot that has a lot of people walking around. Make sure it's an appropriate place, then watch people break fingernails to get the coins.
Put a potato in the exhaust pipe of the car. The car would not start. Paint the potato black so that the victim cannot see the potato.
Interchange the ground salt and ground sugar and enjoy the agony of the cook.
Rub a baby/massage oil to the taps/window knobs(only the circular types). The victim would find it difficult to open the door or tap.
Tie a knot to the laces of both the shoes with each other. But avoid doing it on elders as they may trip and hurt their fragile bones.
Take a brownie and form it to look like dog poo. Place it on the grass of the victim's yard. As you and victim pass by, point it out to the victim, bend over and examine it. Then grab it and put it into your mouth; or throw it at the victim. The victim will get a momentary shock until they figure out they've been tricked.
Get up early to unplug the toaster. If the cord is normally visible find a cord that looks similar, plug it in and hide the rest behind the toaster. Besides not working, most toasters won't even lock the toast down when you push the pedal. Just make sure you're there to watch your victim become frustrated as his toast keeps popping back up!
Take a picture of the top part of the kitchen counter. Go on the Internet and search for a picture of a cockroach. Then, copy it on to the picture of the counter. Print out a few copies (cut off any extra white space), and place them on the counter. At first glance, your victim will think the kitchen is infested! You can use the pics of mice also.
Go to the video store with the victim and have them pick out some movies they want to watch. Then when you get home, have them go get some snacks or something and while they're distracted, switch the DVDs inside the cases with some really lousy movies you know they'll hate. Then laugh when they think that the video store gave them the "wrong" movies!