Denis Hof -- the owner of the famous Moonlite Bunny Ranch brothel in Nevada -- tells TMZ ... he once had a client who paid more than $2 MILLION to nail his hookers on Christmas Day ... HO HO HO!!!
Hof -- who stars on the HBO show "Cathouse" -- was on the way to get a Thai massage in L.A yesterday with one of his whores when we decided to talk shop ... and by shop, we mean prostitutes.
Among the talking points -- Hof told us he's confident he's going to win his lawsuit against his former prostitute Jimi Lynn ... who allegedly hid hundreds of thousands of dollars in gifts from the whorehouse.
Hof says he has various measures in place to make sure the rest of his hookers stay honest -- including a "secret shopper" program who "test the girls and make sure they're doing the right thing."
We broke the story, Hof has signed Tiger Woods' former mistress Joselyn James to moonlite at the ranch ... but now, Hof says he's hoping to get ANOTHER celebrity mistress aboard as well.
As for the mystery hornball who dropped the $2 mil ... Hof wouldn't reveal his identity ... but assures us the dude got his money's worth.