My memory is pretty craptastic, BUT I very much relate to trying to erase something vocally. I do it when I start to hear any music that I fear getting stuck in my head. (If it is something I like, that is not such a fear).

As soon as I hear such a thing, some things I do:
Plug my ears with my fingers and hum very loudly or say, we-ew we-ew we-ew (like siren)
Cover my ears with my hands and rapidly repeat something like, "nah nah nah nah nah" very flatly.
Make random off-key note sounds (the AntiCatchy, lol)
Shout, "no no no no no"

You get the idea. I don't care where I am. THEY aren't the ones who are going to hear it looped for days or more likely weeks, so I don't care what they think. The vocalizations are my only hope of preventing this.

I got a perfect score on my ACTs back in the day, so not "mentally challenged" at all in the sense you mean. (Which is not to say I haven't lost a lot of ground in processing, like executive functioning). So I don't think it reflects your intellect at all. Is that your concern, pirilin?