Some Like It Hot (1959)

Two struggling musicians (Curtis & Lemmon) witness the St. Valentine's Day Massacre and try to find a way out of the city before they are found and killed by the mob. The only job that will pay their way is an all girl band so the two dress up as women. In addition to hiding, each has his own problems; One falls for another band member (Monroe) but can't tell her his gender, and the other has a rich suitor who will not take "No" for an answer.