While most of the things that you can't take on board an airplane are fairly obvious (guns, knives, explosives), there are some things that most people wouldn't think about. Who would have thought that a smoke detector could be considered hazardous? If you do transport a hazardous material on a passenger plane without declaring it, you could face a fine of up to $27,500! Make sure you contact the local airport authority if you have any concerns about an item you plan to carry with you on a trip.
Because terrorism is a constant and terrifying threat, this means that any mention of certain words, such as "bomb," "hijack" or "gun," can lead to your immediate removal from the plane and quite possibly your arrest, even if the word is said in an innocent manner. Everyone who works in aviation, from flight attendants to security personnel, is trained to react immediately to those words.