How much of a role do surprise and company play in making a song enjoyable to listen to?

I was thinking about this the other day when a certain song came on my car radio that I was sure the station that was playing it would never play. I got pretty excited and enjoyed hearing the song in my car, even though I would've never have chosen to play that song myself if given the choice. I forget what the song was, but that's besides the point. That sort of thing has happened to me, and probably you, before in your life. A song, artist or genre that you would could say to be "sick of" comes on at an unexpected time and all of the sudden this unexpected sense of fun takes over and you appreciate the song on a level you didn't think you could ever have again.

If I were asked to pick from a thousand songs on my computer to play for myself I probably wouldn't want to pick that song, but when it happens to randomly come out of some radio station's playlist I seem to take a great enjoyment in hearing it again. How does this work?

Another directly related question is why is it that people appreciate songs differently in the context of it unexpectedly coming on a radio, or during a party, or over a supermarket speaker than would if they could listen to that song at a later time at their own leisure?

Is it the sense of being surprised by the song that makes it more enjoyable? I mean, anybody can enjoy about any song at their leisure and by themselves, but you can't always enjoy that same song with someone else all the time and through these circumstances. So is it because people have more fun listening to songs in the company of others that makes it more enjoyable? Even if those "others" don't always exist as far as they know do they enjoy the idea that they are now experiencing some sort of "community listening" to a certain song? Is this why some people would rather hear a "B" song over the radio than an "A" song all by themselves?

What say you?