Picture this: the year is 1975, and the country is in turmoil from decades of war and lousy with hippies. A grizzled old Sailor goes back to his hometown on leave, hoping to meet up with high school buddies he got drafted with, but no one shows. He ends up going to a bar by himself and gets a beer.
A college-age girl sees him with his Navy tattoos and decides to lecture him on the evils of war and the military/industrial complex. Almost immediately sparks fly and the conversation flows toward much more interesting topics, they share a few drinks, and before they know it, both of them are pretty loose.
The girl decides to broach more adult topics and asks the Sailor when was the last time he had sex.
The sailor said the last time he was intimate with a woman was 1950.
The coed decides that simply will not do and asks the Sailor to come home with her right away.
The Sailor and the girl end up having wonderful sex, the best sex she's ever had. Afterward, she asks the Sailor how he was so good in bed after not having had sex for so long.
The Sailor looks at the girl, puzzled, and says, "Ma'am, 1950 was four hours ago."