Nothing says "prepare to get your ass kicked" like the shark's mouth painted on the aircraft of the famous Flying Tigers. Below is an except from the www.answers.com article on the Flying Tigers. If you click on the title of this post, you'll be directed to the entire article.
The photo was taken by one of the Flying Tigers, R.T. Smith. It is copyrighted and used by permission. The story about the photo itself is pretty interesting:
Flying Tigers (Traditional Chinese: 飛虎隊, Simplified Chinese: 飞虎队; pinyin: Fēi Hǔ Duì) was the nickname of the American Volunteer Group, a fighter unit that fought in Burma and China, against Japanese forces during the year prior to the United States participation in World War II. After the dissolution of the AVG in mid-1942, the name was applied to its successor military unit, the 23rd Fighter Group, and more broadly to the China Air Task Force and the U.S. 14th Air Force. The shark faced fighters remain among the most recognizable of any individual combat unit of WWII, and they demonstrated innovative tactical victories when the news was filled with nothing but defeat after defeat by the Japanese at the start of WWII before American involvement.
The Flying Tigers had their first combat on December 20 1941, when they shot down three Japanese bombers near Kunming and damaged a fourth sufficiently that it crashed before returning to its airfield in northern Vietnam. The 3rd Squadron — 18 planes strong — defended Rangoon in December 23-25 and claimed approximately 90 planes, most of them heavy bombers. Other squadrons were rotated through Rangoon in January and February 1942. After the fall of Rangoon to the Japanese in March, the AVG was redeployed to bases in northern Burma and finally in China. Not surprisingly, later research has shown Japanese losses to have been smaller than believed at the time. The AVG was officially credited with 297 enemy aircraft destroyed, including 229 in the air (some popular accounts inflate the total to 500 or even 1,000 planes), but author Daniel Ford calculated that the AVG actually destroyed about 115 enemy aircraft in the air and on the ground.
Thirteen pilots were killed in action, captured, or disappeared on combat missions; two were killed in ground accidents; and eight were killed in flying accidents during the Flying Tigers' existence. One of the more famous pilots was Gregory "Pappy" Boyington, who was dishonorably discharged in April 1942. He went on to command the Black Sheep Squadron, with many similarities to the Flying Tigers, and was one of two AVG veterans (the other being James Howard of the USAAF) to be awarded the Medal of Honor in combat. Other notable AVG veterans were David Lee "Tex" Hill, later commander of the USAAF 23rd Fighter Group; Charles Older, who postwar earned a law degree, became a California Superior Court judge, and presided at the murder trial of Charles Manson; and Kenneth Jernstedt, long-time Oregon legislator and mayor of his home town of Hood River.
Many in China have not forgotten the Flying Tigers. Many model aircraft bear the slogan "Ding Hao", which means "very good" or "hot stuff" in Chinese, and there are pictures and movies of Chinese making a thumbs up gesture at American pilots. Some Chinese fathers who lived from the period told ther sons that it was actually the American pilots who picked the Chinese gesture for "you are number one", and people from China today can confirm the meaning of this gesture. This gesture appeared about the same time as the AVG deployment.
Thumbs up remains a common signal among US and other combat pilots. The blood chit on the back of leather flying jacket complete with Chinese writing and flag is still a common fashion statement even to those who have never heard of the Flying Tigers. Toy and hobby stores still stock model and toys of shark mouthed Tomahawk, some with the Chinese nationalist insignia. One 1960s magazine even featured a flying tiger shooting peas in a food magazine. The tactics used in combat to maximize the effectiveness and minimize the weakness of your own planes would be relearned over Korea and Vietnam with creation of specialized air combat schools such as TOPGUN and designing fighters specifically for combat agility after America had entered every war with fighters deficient in maneuverability.