♫ Hey mister, hey mister writer, you're not a DJ. Turn the music down! ♪
Times mentioning a specific song is allowed:
1. Karaoke scenes
2. Dichotomy (a happy song over a fight scene, etc...)
And even then you should use 'a song like...' This lets potential producers and directors know what's going on in the scene without locking them into an expensive song.
Even better for you, it lets them know you're a professional who will not crazily think the script must be your 'vision.' It's the producer and director's vision, it's just your script. (Even if you don't believe that, that's the company line. Learn it well.)
Writers who are delicate about their 'children' don't get called back. Writers who insist that the song on the radio must be The Jam's "Waterloo Sunset" may have good taste in tunes, but will also have a bad rep with their reader.
Yes, established writers break this rule. But they got to be established by proving they weren't fussy, helicopter-parents. So tuck it back in your pants.*
*and by 'it' I of course mean your iPod
