Yes, the pig one actually works. The seniors at my school two years back did it with chickens, labelling them 1, 2, 3, 5(they had 4 chickens) and let them loose in the hall. The administration was looking for #4 all week
Watching the initial chicken race wasn't half bad either
Also, with a few pbc pipes a pbc joint thing(i dunno its technical term) and 3 shots of hairspray you can make a golfball cannon. Put the golfball in, which is stopped at the join, and on the other side have an area to hold flammable material(small chamber of sorts) put in three shots of hairspray/other flammable gas and light with a match. Don't put hand behind w/e hole leads to the flammable gas, light it indirectly if possible, or just hold the match near until it ignites, its very forceful and very dangerous. My friends were able to put a decent dent in solid wood with it. Beware, more than 3 shots of hairspray causes dangerous hair burning backfire, so do 3 at the most. Also, don't point towards civilization in general, the golf ball goes a long way with a lot of force.
Also, look up "Elihu-Thompson" coil. With a capacitor big enough an elihu thomspon coil is capable of leaving a purplish/red welt on a person. Don't point at eyes. That hurts the most. Weapons are great, science weapons are gooder :P Cuz you can always tell your principle its made in the name of science, and honestly, no one knows what you're doing when you show up with an elihu thompson coil, it looks harmless until you charge it up and launch a ring. Note: ring can't have a break in it, or the current that would propel the ring forward would dissipate into the air and no reaction would occur. Physics rawks