Mumble is the equivalent of whispering to yourself. Mumble is speaking quietly, and muttering something under your breath, not needing anybody in specific to hear your words. An example:
mumble Fuck that snobby bastard.
How others will see it:
Joe mumbles, "*something unintelligible*" under his breath.
However, just like whispering or talking quietly into a phone, some characters can overhear your words and can react to them ICly!
*Last Updated: 06/11/23 by Fengshui*