When perhaps, after which a male may have been engaging in physical behaviour performing a task, such as moving some heavy boxes, lifting heavy furniture, or other similar tasks, on behalf of the request of a female friend, of which no romantic links are intended, when during or after finishing the task/s, becomes aroused, has no control over the organ, has to stand and continue talking to the friend with the erection clearly seen, and then commented on by the female. Its when asked, if he is aware of the quite obvious display of arousal by the female, and then answered, that the offending organ was not intended for, or induced by,nor poses threats of any kind toward her, that it is then deemed a Platonic Boner. The female, at this point, as a courtesy, is obliged to give a few moments for the genitals to deflate to normal dimensions, and to accept that it was in fact, platonic. Any changes to his intentions from that point onwards, returns the state of the hard-on back to one of being normal, that is, of the intent to be inserted, rubbed, or stimulated by any other means to the eventual point of orgasm. Platonic Boners, once achieved, may be, and now commonly, conciously sustained for periods of time, as a form of practice for Tantric sex sessions, and socially accepted as practice for such, so long as the intent is clearly defined and can be proven to be as practice for these sessions when asked, and if the groin area, clearly shows attempts at disguise.
A super hero may be rescuing a woman from a burning building, places her safely back on solid ground, the woman noticing a large bulge in his pants, indicating an erection, and when just about to say something to the rescuer, he announces that there is nothing to fear, it's just a Platonic Boner. The woman then goes home and tells everyone that she has seen supermans willy, without fear of being labeled a whore