TMZ has learned ... one of Tiger Woods' mistresses was fired from her job as a "working girl" at Nevada's most famous brothel ... all because she opened her big fat mouth.
Devon James -- mistress number 20ish -- is still featured on the website for the world famous Bunny Ranch in Carson City, where owner Dennis Hof confirmed Devon was employed as a sex worker for "a while."
But Hof tells us he recently fired Devon's ass after she injected herself into the Tiger Woods media circus because she "broke the code -- which is privacy and discretion with all clients."
Hof continues, "She is a disgusting excuse for a working girl ... she's a scumbag and a snitch."
As for Devon's rate during her stint at the ranch -- Hof explains, "It's negotiable depending on what you want ... but it could get into the thousands."
Hof ended with this parting shot -- "Now that she doesn't work here anymore ... I wish nothing but the worst for her."
A rep for Devon tells us, "She worked there one time before the Tiger thing."
The rep also insists that management at the Bunny Ranch continues to call Devon because they want her to work there.