I did that little experiment a couple of years ago with “Recovery” by LP when I took a song with no bass part at all and just tried quickly to come up with a bass line from zero. And you know what, I liked that :) I mean, it's kinda cool to imagine WHAT IF a song had a bass line... and not just improvise but try to come up with something that would sorta suit the song. I seriously encourage you to try it, it's funny as a bunch of rabbits!
Here I tried it again with the song “Ich boykottiere dich” (“I Boycott You”) by one and only Grossstadtgeflüster, a German electro pop/punk band my wife and I both love very much. And it's one of my wife's favorite songs too, so I just tried to push myself a bit further :) Just in case you hate it and just-leave-our-fav-song-alone-you-pervert, relax, the song is perfect as it is and what I did is just my own take on “what if”, not more. Take it as a game :)