Celebratory gunfire
Celebratory gunfire is the shooting of a firearm into the air in celebration. It is culturally accepted in parts of the Balkans, Russia, the Middle East, Afghanistan, Pakistan, Guatemala, Ethiopia, Mexico, even where illegal. Common occasions for celebratory gunfire include New Year's Day as well as religious holidays. The practice sometimes results in random death and injury from stray bullets. Property damage is another result of celebratory gunfire; shattered windows and damaged roofs are often found after such celebrations. Falling-bullet injuries. Bullets fired into the air usually fall back with terminal velocities much lower than their  muzzle velocity when they leave the barrel of a firearm. Nevertheless, people can be injured, sometimes fatally, when bullets discharged into the air fall back down to the ground. Bullets fired at angles less than vertical are more dangerous as the projectile maintains its angular ballistic trajectory and is far less likely to engage in tumbling motion; it therefore travels at speeds much higher than a bullet in free fall. A study by the U.S. Centers for Disease Control and Prevention (CDC) found that 80% of celebratory gunfire-related injuries are to the head, feet, and shoulders. In Puerto Rico , about seven people have died from celebratory gunfire on New Year's Eve in the last 20 years. The last one was in 2012. Between the years 1985 and 1992, doctors at the King/Drew Medical Center in Los Angeles, California, treated some 118 people for random falling-bullet injuries. Thirty-eight of them died. Firearms expert Julian Hatcher studied falling bullets in the 1920s and calculated that .30 caliber rounds reach terminal velocities of 90 m/s (300 feet per second or 186 miles per hour). A bullet traveling at only 61 m/s (200 feet per second) to  100 m/s (330 feet per second) can penetrate human skin. In 2005, the International Action Network on Small Arms (IANSA) ran education campaigns on the dangers of celebratory gunfire in Serbia and Montenegro. In Serbia, the campaign slogan was "every bullet that is fired up, must come down." Property damage. Bullets often lodge in roofs, causing minor damage that requires repair in most cases. Normally, the bullet will penetrate the roof surface through to the roof deck, leaving a hole where water may run into the building and cause a leak. Cultural references. The non-fiction U.S. cable television  program "MythBusters" on the Discovery Channel covered this topic in Episode 50: "Bullets Fired Up" (original airdate: April 19, 2006). Special-effects experts Adam Savage and Jamie Hyneman conducted a series of experiments to answer the question: "Can celebratory gunfire kill when the bullets fall back to earth?" Using pig carcasses, they worked out the terminal velocity of a falling bullet and had a mixed result, answering the question with all three of the show's possible outcomes: Confirmed, Plausible and Busted. They tested falling bullets by firing them from both a handgun and a rifle, by firing them from  an air gun designed to propel them at terminal velocity, and by dropping them in the desert from an instrumented balloon. They found that while bullets traveling on a perfectly vertical trajectory tumble on the way down, creating turbulence that reduces terminal velocity below that which would kill, it was very difficult to fire a bullet in this near-ideal vertical trajectory. In practice, bullets were likely to remain spin-stabilized on a ballistic trajectory and fall at a potentially lethal terminal velocity. They also verified cases of actual deaths from falling bullets.