I’ve been playing for [mumble] years (and boy, are my fingers sore). I use “Layla”–a song I don’t mind hearing in my head, and good enough that it drives out anything else.
I forget where I read this, but it works for me.
Hum “The Girl From Ipanema” (don’t sing it, just hum the tune) and within moments, the original earworm, as well as Ipanema, are gone.
I think of that as a pro rather than a con. 
Just kidding. I see your meaning. Maybe if you hum something ‘internally’ it will be, you know, slightly less wierd.*
*Warning. Your national anthem is not intended to be taken internally. If jingoism persists, please see your physician.
Here’s an old thread. See my post (#7) for what worked for me. YMMV.