We both worked at McDonalds (which made things a bit awkward when we broke up, although I'm happy to report that nearly everyone sided with me), and one of our managers (Greg) was constantly giving her a hard time for not treating me well - and I should note that those were his words, not mine. After a while, to make his point he'd just start singing "What you gonna do when HE says goodbye...?", until I asked him to stop on the theory that his (not so) subtle dig wasn't helping matters any.
In any event, this song (which, frankly, you don't really hear much anymore) always takes me back to that time. From the summer of 1977, Pablo Cruise, with "Whatcha Gonna Do?"