Top definition
someone who is talkin shit. most likely drunk, possibly even a two faced hoe. a mouth runner is always talkin all sorts of trash as if they're life is a high school rivalry.
did you hear what she said? fuckin mouth runner..

them tuscarawas county bitches are the best mouth runners.

i bet that mouth runner is going to the gathering..
by realboy01 June 07, 2010
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