definition of rape. Seems that in the UK victim has to be penetrated by a penis in any orafice, so men and women can be raped, but only men can be rapists. There is another offense of assault by penetration if something other than a penis is used.
But if a person forcibly gets a man to penetrate them with their penis it is not "rape". I am probably being very naive here, but I actually don't see how this scenario is physically possible. Can a man get an erection under these circumstances?