Do you know what "whippersnappers" are? The little white calls of paper filled with a bit of gun-powder, shaped like a mini-tadpole that explode when you throw them at the ground. Some people call them "bang snaps". Here's a photo: Anyways, I was telling jonaswildman that I had bought some to show to my daughter and he mentioned that when he was a kid he and his brother used to put them under the toilet seat as a prank to his mom and dad. The things are pretty loud and if you sat on a toilet seat and one went off, you would definitely be freaked out. I put one under our toilet seat in our bathroom the other day and chickened out before my wife ever sat on it. It just seemed too mean.
Oh, yeah, and from wikidedia: Bang snaps consist of a small amount of gravel or coarse sand impregnated with a minute quantity (~.08 milligrams) of silver fulminate high explosive and twisted in a cigarette paper to produce a shape resembling a teardrop with a tail. When stepped on, ignited, or thrown on a hard surface, the friction-sensitive silver fulminate detonates, producing a sharp salute similar to that of a cap gun.
Despite producing a legitimate (albeit tiny) high-explosive detonation, the extremely high mass ratio of gravel to explosive acts as a buffer to ensure that the devices produce only the audible "crack" of the supersonic shockwave; they are incapable of producing physical damage, even if discharged directly against skin, and the detonation frequently fails to even break the thin paper holding the ingredients.[2] The explosion is also too weak to propel the gravel any distance, which usually falls to the ground. This makes them safe for use as a children's toy, for which purpose they have been widely sold across the world since the 1950s. They are also a common part of Chinese New Year celebrations."