Things lady covers the basics well, but this time of year you may have some interesting gifts you are questioning about placing in your carry on...
Things you also can't bring on a plane ...Magic 8 Balls (it's filled with liquid), Gel Insoles (this is a gamble some may or may not make you dispose), Ice Cream, Nerf or Water Guns (that should be common sense), and something you can't bring in your carry on or checked baggage - Medical Marijuana. It may be legal in some states but under Federal Law marijuana is illegal.