As I watch (for 1000th time) American Dad's "In Country...Club" (S05 E01), I'm amazed at how good the episode is. Probably because I always loved vietnam war movies and parodies. This spoof was really well done and if you haven't seen it I strongly advise you to get to it !
It made me think of all the different sitcoms that played Samuel Barber's "Adagio for Strings" in reference to Platoon.
So I researched "Samuel Barber" in IMDB and here is a list of episodes that feature that particular piece in chronological order :
Seinfeld : S08 E06 - "The Fatigues" 1996
The Simpsons : S14 E09 - "Strong Arms of the Ma" 2003
South Park : S08 E 02 - "Up the Down Steroid" 2004
The Simpsons : S18 E17 - "Marge Gamer" 2007
The Simpsons : S19 E06 - "Little Orphan Millie" 2007
American Dad : S05 E01 - "In Country...Club" 2009
How I Met Your Mother : S05 E13 - "Jenkins" 2010
Most of the time, Samuel Barber wasn't credited for "Adagio for Strings" in these episodes.
The movie
Platoon came out in 1986 and the "Adagio for Strings" was featured in movies and documentaries as well as sitcoms before but mainly after
Platoon.
When Does "Adagio for Strings" Appear :