Has anyone ever thought about how it's wild that vaginal orgasms and prostate orgasms are so coincidentally similar in experience, or is it just me?

Actually, despite myths to the contrary, male and female orgasm in general are, to the extent we can tell, very similar. For example, a study by Vance and Wagner (1976) found that expert panels were unable to identify the sex of study participants based on their description of orgasm. Mah and Binik (2002) similarly found that male and female orgasm are substantially the same and could be described with the same model. A study by Georgiadis et al. (2009) also found that brain activity during orgasm was substantially the same for males and females. All of this is not arguably not particularly surprising, considering orgasm presumably uses similar neural and hormonal machinery in both sexes.

Sources:

Georgiadis, J. R., Reinders, A. S., Paans, A. M., Renken, R., & Kortekaas, R. (2009). Men versus women on sexual brain function: prominent differences during tactile genital stimulation, but not during orgasm. Human brain mapping, 30(10), 3089-3101.

Mah, K., & Binik, Y. M. (2002). Do all orgasms feel alike? Evaluating a two‐dimensional model of the orgasm experience across gender and sexual context. Journal of Sex Research, 39(2), 104-113.

Vance, E. B., & Wagner, N. N. (1976). Written descriptions of orgasm: A study of sex differences. Archives of Sexual Behavior, 5(1), 87-98.

vulpes_artifex said:
Actually, despite myths to the contrary, male and female orgasm in general are, to the extent we can tell, very similar.

Yes, that's exactly what I was saying! I don't think I read it at any of those sources, but it was one of things I picked up somewhere. I think it's crazy coincidental that they're an extremely similar experience. It makes me wonder if evolution intentionally did that for connection reasons.

I also heard that the female orgasm was a mutation that just stuck around, but I have a harder time believing that: If both parties can't ever enjoy it, wouldn't that be bad for reproduction?

cypress_cat said:
Yes, that's exactly what I was saying!

Right, but you were limiting it to prostate orgasm, when it actually applies to penile orgasm as well.

vulpes_artifex said:
Right, but you were limiting it to prostate orgasm, where is actually applies to penile orgasm as well.

Really? I've never heard of penile orgasms described as whole body experience type thing like I've heard prostate, vaginal, and even anal O's to a less degree.

cypress_cat said:
Really? I've never heard of penile orgasms described as whole body experience type thing like I've heard prostate, vaginal, and even anal O's to a less degree.

I suspect there's a lot of things at work that make those orgasms seem more intense and widespread, like gender expectations and location in the body. But the science says that as a general rule, penile orgasms are as good as any.

As for why, I suspect it's mostly down to developmental homology—that is, all kinds of orgasms use the same neural and hormonal machinery, so naturally they feel similar.

cypress_cat said:
Yes, that's exactly what I was saying! I don't think I read it at any of those sources, but it was one of things I picked up somewhere. I think it's crazy coincidental that they're an extremely similar experience. It makes me wonder if evolution intentionally did that for connection reasons.

I also heard that the female orgasm was a mutation that just stuck around, but I have a harder time believing that: If both parties can't ever enjoy it, wouldn't that be bad for reproduction?

It's not a coincidence, exactly! Most things between males and females are the same stuff and just shifted around... a lot. But it's all different forms of the same thing. Hence why male and female orgasms are so similar (I'd even argue almost identical, just the stimulation itself is different, and even then probably not as much as we think), and why basically almost every single female mammal also experiences orgasm. It's all the same triggers from similar nerves, muscles, etc. Just shifted around and taking different shapes due to very small changes in utero.

Though it all depends on how someone defines 'similar' and 'small changes'. Developmental homology, as Vulpes pointed out, is the key here to why this is, and based on this it's really basically 'the same', just shifted around and reused for different things.