Simpsons Season 9, Episode 25: Natural Born Kissers

Homer and Marge go out on their anniversary dinner, but are forced to take the kids. They end up having an unromantic dinner, and lose interest in being intimate later that night. Later, the two must go purchase a new refrigerator motor, but during a rainstorm, their car gets stuck in the mud, so the two rush into a barn. When the farm owner nearly discovers them, the two become excited and have sex.