tora tora

Named after the 1970 blockbuster movie Tora! Tora! Tora!, because of its popularity portraying the use of propeller driven fighter planes (mostly WW2 era models), The origin of the word "tora" is from the Japanese 虎 literally means "tiger", but actually, it was an abbreviation of two-syllable codeword 突撃雷撃 (totsugeki raigeki, “lightning attack”) used to indicate that the attack had commenced. And also, the film was notable for using North American T-28 Trojans to simulate IJN Mitsubishi A6M Zeroes.

来源：wiktionary