"Bummer" is rooted in the life and death of Dwight Hal Johnson (1947–1971) a native of Detroit, Michigan, and a United States Army soldier who received the Medal of Honor for his actions in January 1968 during the Vietnam War.
Just after 11:30 PM on April 29, 1971, Johnson was shot during an armed robbery at an Open Pantry Market convenience store about a mile from his home, in Detroit. Although wounded in the left biceps, during the altercation the store owner opened fire with a .38 caliber handgun. Johnson sustained four bullet wounds, three to the chest and one to the face, and died on the operating table at 4:00 AM on April 30. He was buried in Arlington National Cemetery on May 6, 1971. His grave can be found in Section 31 Lot 471.Johnson’s mother said: “Sometimes I wonder if Skip tired of this life and needed someone else to pull the trigger”.

The Medal of Honor is the highest military award given to a service man or woman who has gone "above and beyond" the normal call of duty in service to his or her country.

The Purple Heart is a military badge given to a U.S. service man or woman who has been injured while on active duty in their service to the country.

An agricultural tool widely used in cutting down weeds or stalked plants. Some folks call it a sling blade.

Before it was made harmless, a simple bottle of airplane glue, to be used on model airplanes and other types of models you had to put together by hand, was enough to make a determined hobby enthusiast "high." The glue was often purchased for the ease of availability, being completely legal, and after the dangers it posed became aware to the general public (Thanks in large part to comedian Lenny Bruce making a killing with his jokes about sniffing it) another ingredient was added to the glue to detoxify the effects of sniffing it.

Skag is one of the many nicknames of heroin. It is highly addictive and mainlining means to inject the heroin into one's bloodstream by a hypodermic syringe.

Refers to Fayetteville National Cemetery, located in Fayetteville, Arkansas. Not as highly revered as Arlington National Cemetery, where most medal of Honor awardees would prefer to be buried.

Arlington National Cemetery is a United States military cemetery in Arlington County, Virginia, across the Potomac River from Washington, D.C., beneath whose 624 acres have been laid casualties, and deceased veterans, of the nation's conflicts beginning with the American Civil War, as well as reinterred dead from earlier wars.

Veteran's Administration. Or more appropriately, the United States Department of Veteran's Affairs, a cabinet level entity entrusted with the care and concerns of United States military veterans.

A derogatory term for white people that was popular for a short while in the 60s. Some saw it as an attempt by the black populace to find an appropriate comeback to dreaded "N" word used by some people throughout history.

Viet Cong. The political and military arm of the North Vietnamese government. Harry seems to sway between the Vietnam conflict and the Korean conflict in this song, but really, it could be intentional by meaning to represent all wars and conflicts.

Another derogatory term for Asian people. Again, Harry is using terms such as "gook" and "slants" to show the mind of the soldier's dehumanizing process that war embeds in the military.

The "A&P" is the commonly referred to name of the Great Atlantic and Pacific Tea company, which was once a major grocery store chain that spanned the United States.

"Gook" is a derogatory term American military servicemen applied to Koreans. Harry is utilizing the term as to put one in the mind of the American military soldier during the Korean War, emphasizing how war dehumanizes people's compassion.

Demilitarized zone. The demilitarized zone between North and South Vietnam was established in April 1954 as a result of the Geneva Conference ending the war between the Viet Minh and the French. The DMZ in Vietnam officially lay at the 17th parallel; in reality, it extended about a mile on either side of the Bến Hải River and west to east from the Lao border to the South China Sea.

Harry Chapin's son, Josh, admitted years after his father's death that this part of the song was not true. He was never sent up with a note from his teacher saying this part, as Harry claimed. It was just a bit of poetic license.