this prank is pretty simple, with very destructive and stressful results. it ends with the toilet overflowing with an emulsion of carbon dioxide bubbles.
sorry for the slight lack of pictures. I don't have a legit camera, so I took most of them on my computer's webcam and one of them with my cell phone.
Step 1: Ingredients
these ingredients are fairly simple. the only thing you could have a problem with is the citric acid, which you might be able to find on the internet. I found mine at an amish store.
Step 2: Add Citric Acid and Soap to the Tank
this step is pretty straightforward. the only thing I would have to say is that the tank should have a lot of citric acid in it. like, a lot. I would say put about a cup in there. maybe a cup and a half to be safe. try to put as much as you can in. same with the soap. about half the bottle should work.
also, try to mix as you put it in. the citric acid should be dissolved as much as possible. same with the soap.
why not use vinegar, you say? well, for two reasons. first, vinegar is very voluminous. it would take too much space. second, it is smelly. you would be given away when the bathroom smells like nasty.
Step 3: Put Baking Soda in the Bowl
the baking soda should definitley be dissolved as much as possible. I would say to just keep adding it until you see the stuff start to collect at the bottom and you can't make it dissolve. then you know it's saturated.
I would say this should also be about a cup of baking soda.
Step 4: Wait for Your Devilish Plot to Unfold
the toilet, when flushed, will release a large amount of suds. it's not like in the picture, but that was the only one I could find. it's actually better my way, because the toilet suds will suddenly bubble up and leave the toilet almost immediately. they will slop all over the floor and the person will be struck so fast that they won't know what to do.
don't do this if you don't want to help someone clean up a large, large mess. it will be very messy. you might want to use antibacterial soap just in case.