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This is a classic prank that's easy and annoying as hell. It was pulled on me a few years ago and I was pissed, but impressed.
In the following steps I will explain how to put together a water-based obstacle that will annoy anyone and everyone and add a few tips for making it really evil.
Step 1Materials: cups and water
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I recommend little Dixie cups because I find they make this most annoying, but any plastic cup will do, large or small. You also need a water source (sink, bucket, bottled water, whatever). Depending on the size of the area you're going to prank, you may need a lot of cups and a lot of water (i.e. you might have to spend some money).
D
Milk, Old milk
And set it up at night, while they are asleep, because you probably wont get caught.
1: I'd be cleaning it up, not the student the prank was pulled on.
2:I'd would not be cleaning the bathrooms or taking out the trash that day because I'd be to busy trying to get all the crap up and out of the carpet
3:If no one stepped up and claimed it then the entire hall would be charged for the cost of cleaning/damages
All I'm saying is take a moment and think of who would actually have to clean it up.
And don't forget the janitor has control of the toilet paper.
If nothing was going to be hurt by it, I would just walk (roll my chair in my case) right over them.
-Fill the cups up almost completely instead of halfway. This will make cleaning it up tougher.
-Use fishing line to make a tripwire. When they're cleaning, they will trip and spill some, while landing on the rest of the cups.
-Put a drop of something clear and disgusting into each cup. When cleaning it, they may take a sip of the water (instinct) and be grossed out. Some good ideas are: Lime juice, Castor oil, etc.
-Fill the cups with something that stinks.
-Use duct tape to make a giant floor of cups. Make 2x1 cups, put 2 together, make 2x2 cups, put 2 together, make 4x2 cups, put 2 together, make 4x4, put 2 together, etc. untill you have a giant unit of cups which you can fill up with a bottle/pitcher.
-Think up yo own!