The chorus, from the song title, is routinely used for any causes for celebration and optimism, much like elected representatives on the campaign trail reflexively promise better days to come – if you were to elect them and only them. It’s also a popular tune at school graduations.
Ummm… apparently the song is actually about needing sunglasses to shield one’s eyes from the bright lights of an exploding nuclear holocaust! It’s from 1986, during much Cold War consternation.
Listen more closely to the lyrics, folks!