Stripes (1981)

Hard-luck cabbie John Winger (Bill Murray) -- directionless after being fired from his job and dumped by his girlfriend -- enlists in the U.S. Army with his close pal, Russell Ziskey (Harold Ramis). After his barely satisfactory performance in basic training, the irreverent Winger emerges as the figurehead for a ragtag band of Army misfits. However, his hijinks threaten to cause an international scandal when he inadvertently commandeers a military assault vehicle behind enemy lines.