With tens of thousands of songs from all the decades behind my back, it is just impossible to pick one. My 80's folder alone is about 2500 tracks, I really just can't settle on one.
But if I have to... well, the hymn to the 80's is, arguably, this song:
Released right in the 1985 to top it off. Though, frankly, while the theme of the song is spot on, I find the sound rather punk and far from the... flamboyant sound of the decade that has been in the mainstream of the era.
Shame that, like, the 50's do not have a song by Elvis Presley or Chuck Berry shouting "Fifties!", so I'm quite lost in the amount of songs for any other decade. It also doesn't help that 50's songs from US are rather different from the songs from, like, Soviet Union.
At least starting with the 80's the sound of the music started to get... generalized across all countries, and cantopop from Hong Kong doesn't sound too different from american synthpop. Albeit, on the other hand, I'm not quite sure it is a good thing, since it kind of speaks about monoculture spreading around the world.