While these types of toys are generally permitted, we recommend that you pack them in your checked baggage. Squirt guns, Nerf guns, toy swords, or other items that resemble realistic firearms or weapons are prohibited. We recommend emptying water guns, which must follow the 3-1-1 Liquids Rule. Replicas of explosives, such as hand grenades, are prohibited in checked and carry-on baggage. TSA officers have the discretion to prohibit any item through the screening checkpoint if they believe it poses a security threat.