I’ve been trying to find this song, which I remember having pretty wide American pop/rock radio airplay around 1977-79. Google and iTunes have failed me. My memory of it is pretty hazy, but IIRC, it was about a bunch of friends who’d gather on the street corner of their old neighborhood (NYC or Brooklyn, maybe?) to sing together at night. I can’t remember any particular lyrics, other than the phrases “Come on, sing it with me” and “We could sing all night.” If I had to suggest a song that sounded like it, I’d say Paul Simon’s “Loves Me Like a Rock,” but that’s not an exact fit.
I would bet this one is NOT the one you are referring to, because Boney M are decidedly Eurodisco sounding and I doubt this song got airplay outside of Berlin nightclubs, but their “Happy Song” has similar lyrics.
THAT’S IT! I was finally able to get my hands on a CD collection of late '70s pop songs, and there it was. From 1978, right about when I remember hearing it. Many thanks for your help. This puppy’s going on my iPod.