Joe Rogan -- the voice of the UFC -- is taking a stand on transgender MMA fighter Fallon Fox ... saying there's "no f**king way" she should be allowed to get in the ring with a natural woman.
Rogan unloaded on Fox during his podcast, "The Joe Rogan Experience" -- saying, "She calls herself a woman but ... I tend to disagree."
He continues, "She used to be a man ... but now she has had, she's a transgender which is (the) official term that means you've gone through it, right? And she wants to be able to fight women in MMA. I say no f**king way."
"I don't care if you don't have a d*ck any more," Rogan added ... "You're a man without a d*ck."
**WARNING -- VIDEO CONTAINS EXPLICIT LANGUAGE **
(H/T Bloody Elbow)