Smack one's gum

Hi. To tell the truth, this is the second time I’ve asked about “smack one’s gum.”
Previously I had a reply saying that it presumably means making a “smacking” noise while chewing gum. I’d like to know whether you all agree with this. When I looked up the word “smack” in the dictionary, I found a similar idiom, that is, “smack one’s lips.” It is supposed to be the same as “lick one’s lips”, which means to move (your) tongue over (your) lips, especially before eating something good. Likewise, I imagined that “smack one’s lips” may mean “lick one’s gum.” Gum here may not be the chewing gum but the dental gum. So I asked, “On what occasion would you smack your gum?” to get the answer. But for the word “presumably,” I wouldn’t ask it again. What do you think about the expression?

As no one had a better suggestion the first time you asked, I doubt that you will get a better answer now. It’s not a common idiom.

Also, more context is needed to be certain. For example, it’s conceivable (if unlikely) that it means to hit something hard against one’s gum (where the root of the teeth are).

I wondered if it was a misinterpretation of ‘beating your gums’ (wasting time talking without results) or ‘flapping your gums’ (talking aimlessly about nothing in particular).

Thank you for your comments, Beeesneees and Dozy. The expression has appeared a few times so far while I’m reading. That’s why I’m curious. I’m sorry I didn’t give you the context. Now I’ll quote a few lines from the book.

  1. When I got to the bus stop, there stood Darcy with a purple bag just like mine. I pointed at it, incredulous. “You got my bag.”
    “I know,” Darcy said. “I decided I wanted it. Who cares if we match?”
    Hadn’t she been the one to say that matching was babyish? “I care,” I said, feeling the rage grow inside me. Darcy rolled her eyes and smacked her gum. “Oh, Rachel, it’s just a bag after all …”

  2. “How did it go?” she asks again, smacking her gum. She can’t even wait until she gets home to get the scoop on my date.

What do you think?

She is making a smacking sound with the chewing gum she is eating.
The context makes it clear.

oh, i think the expression is used to express the anger or rage, it means to speak when you hold yourself from saying something very harsh with your fists closed tightly. that is you are controlling your anger and d’not want to show others that you are in anger.

That is not correct Sidrajabeen. It has nothing to do with smacking your fists. It is about making a sort of smacking noise with chewing gum when it is in your mouth.