11/04/2012 09:49 am ET Updated Jan 23, 2014

What You Can (And Can't) Carry Through TSA Checkpoints

A cannonball. Somebody was actually brilliant enough to pack an explosively-viable cannonball into their luggage. A cannonball.

In the annals of idiocy, few can beat what the Transportation Security Administration (TSA) finds daily in luggage. Chainsaws, grenades, grenade launchers, loaded guns, warheads, mortar and bazooka rounds, mines, eels (yes, eels) -- and that's only what has been found this year.

We have all probably had to give up shampoo or shaving cream at one point, and maybe a bottle of wine or a bag of candy. And the logic behind it is simple: Things that appear harmless may not be if a little ingenuity-plus-malevolence is used. Gasoline can look a lot like water, so this is why innocent-looking snow globes get yanked. Gelignite, AKA blasting gelatin, can be hidden in a toothpaste tube, so kiss your "Crest" good-bye.

So what exactly can you get away with? A quick run-through through the TSA's Prohibited Items list hints at a surprising irony: Much of what is removed from carry-ons is perfectly legal if declared and packed in luggage that is checked and stowed. A veritable arsenal of mayhem takes to the skies every day -- pistols, box cutters, knives, hockey sticks, axes, nunchucks, cattle prods -- but are nowhere near human hands and ill intent. Theater-goers across the country scoffed in disbelief when Samuel E. Jackson armed himself with a spear gun in "Snakes on a Plane," but thousands of spear guns are approved daily for transport in passenger jet cargo holds. And if you thought the entire pretense of the movie was "out there," don't: Venomous snakes have been found in carry-ons and checked luggage (but not lei boxes). The fun begins when such items are brought into the cabin.

And just what does the TSA actually do with all the shampoos, knives, guns, and unexploded ordinance it confiscates? Urban legends tell of thievery, auctions, and e-Bay bonanzas, but for the most part, a lot of it simply gets thrown away. Contrary to popular belief, the TSA does not profit from anything it removes. The TSA Blog relates that things that are "voluntarily abandoned" upon inspection, shampoos, liquor, lotions, etc., are tossed in the garbage bin, but other like-termed items are donated according to stipulations set either by the United States General Services Administration or the specific airport. Scissors go to schools. Mace goes to police departments. VA hospitals and non-profits get other items.

All of which begs a final question: what happens to the owners of all the brass knuckles, dynamite, and occasional reptile-that-can't-survive-the-sub-freezing-temperatures-found-in-a-cargo-hold-at-cruising-altitude? Usually just a firm talking-to, but citations and fines aren't off the table. Depending on the jurisdiction, and just how stupid you were, there is also the possibility of a face-to-face with law enforcement officers well-known for having little patience, and even less a sense of humor. One can only imagine the reaction of TSA agents who caught a man en route to Mexico with a kitchen knife and the excuse of "there are no good knives in Cancun."

And as for that cannonball? As it turns out, a diver found it near a Victorian Age shipwreck off the Florida coast. It was quickly found that the coral-covered relic was still live, setting off an evacuation protocol of the Fort Lauderdale Airport's checked baggage area. A TSA explosives specialist and a bomb technician were called in and the weapon was safely disposed of. Three flights were delayed, affecting 290 incredulous and seriously honked-off passengers.

Makes paying a fine look pretty good by comparison. And it makes TAKING FIVE EXTRA SECONDS TO JUST THINK ABOUT WHAT YOU ARE DOING even better. Live Your Indulgence, without your voluntarily abandoned item.