Aircraft Graffiti

Although rarely seen by the travelling public, aircraft graffiti are very common and almost every commercial airliner is tagged in some way, most often in the cargo hold. Other common areas for the graffiti (these are usually written in the dirt or grease on an aircraft) include the engine nacelles, the fuselage under the wing, fuel panels, and landing gear panels, as well as any area of an aircraft where the ground crew work. One well-known case of aircraft vandalism occurred during the merger of US Airways and Pacific Southwest Airlines, when PSA employees painted their company's trademark "smile" onto US Airways aircraft formerly owned by PSA.
In military aviation, fighter crews are also known to write "messages" on the bombs and missiles shortly before leaving on a mission. For example, fighter crews during the U.S. invasion of Afghanistan wrote things like "Eat this, Osama" and "High jack this fags" onto bombs which were dropped during the campaign.
Another form of military aircraft graffiti is the nose art painted on the noses of combat aircraft. Though the practice of decorating planes for battle began among Italian and German pilots in World War I, it was expanded and made famous by the US Air Force during World War II and the Korean War. Some of the images used to decorate fighters and bombers were mascots for the planes, others were Pin-up girls, and many were adorned with gung-ho slogans. Also some military mechanics will jokingly "zap" visiting aircraft by placing stickers representing their own squadron (called zaps) in different areas on the aircraft.