I don't know, I imagine that if you don't think it'll ever happen and no one comes up with a way to make you want it to happen, it probably won't, because it wouldn't matter to you. I think commanding bodily responses based on a specific trigger isn't at all impossible. Pavlov made dogs salivate at the ringing of a bell. It would be a matter of incentive and the target's responsiveness to the training, and probably a great deal of consistency.
The only thing is no one has ever mentioned training males, and I haven't been able to find any links on the matter. I figure recovery time would prevent the matter from becoming a regular event, but no one seems to have even tried it. At least if they have they haven't shared the results with us. Maybe it just isn't a big deal because most people don't consider the effort worth it.

But any other takers on the subject are welcome: Do you think it's possible? If not, why? Has anyone here done so? If so, how? Inquiriing minds want to know.