The person who first shouted "Geronimo!" is unknown, but the phrase is often associated with the Apache warrior Geronimo, who led a band of Apache warriors in resistance against the United States Army in the late 19th century. The phrase is believed to have originated as a battle cry or war cry used by Geronimo and his followers. However, there is no definitive evidence to prove that Geronimo himself was the first person to shout it. The phrase "Geronimo!" gained popularity in the United States in the early 20th century and became widely used in various contexts, such as a cry of excitement or encouragement, or as a signal to jump or take a risk.