Everywhere write that HIV becomes inactive in the environment for several minutes. Why, in this case, there is no risk in mutual masturbation when precum or semen of HIV+ partner reaches the penis immediately, and to the same intensely rubbed? It seems to me that the virus can immediately get under the foreskin and penetrate into the body through its mucosa. I assume that under the foreskin may be no oxygen, which deactivates the virus. I think I am mad for this, because I can not find an explanation to my question. Does anyone know this explanation?