I have this thing I like to do in my writing where characters will open their mouths to speak and then close them again either because they can't think of anything to say or because they're about to crack a joke but catch themselves and realize now's not the time.
This isn't a new or revolutionary concept but I take no shame in admitting that the first place I saw it used, and what inspired me to use it myself, was a cutscene in Sonic Frontiers.