Can you cum without having an erection. There are a couple of ways, like a prostate massage, but I'm talking about being stimulated to the point of orgasm without an erection.
I've often managed to reach to orgasm without having an erection. As already mentioned, prostate stimulation from anal sex can account for some of these, but the others result from masturbation. Sometimes these can be from forcing myself to go for multiple orgasms - i.e. masturbating immediately after having had one orgasm and not allowing the penis sufficient time to recover, but other times have been achieved from when I been absent minded playing with my penis, without consciously masturbating (which I'm actually doing most of the time, as it happens) and once in a while, usually after several hours, it suddenly pops its top. In summary, forced masturbatory orgasms & prostate stimulation orgasm can be mind blowing, but the orgasm reached by sub-conscious masturbation isn't much to speak of at all - it's more of an ejaculation than an orgasm.
In my misspent youth, I'd wank 'til it wouldn't stand up any more. Then learned to wank soft. Possible and profitable. Get going!!
trying to get off while flacid is really uncomfortable, i would rather wait till i actually want to do it