I have to admit that this topic is somewhat interesting to me. As I understand it, most to all mammalian males have a prepuce that covers their glans when flaccid, however humans are the only males in whom the prepuce can cover the glans when erect. This anomaly has prompted some evolutionary biologists to propose theories for this difference. The one that you're referring to, Snoman, seems to be based on Donald Taves' article "The Intromission Function of the Foreskin," which describes the physiological concept behind why foreskin would make rape easier while only devoting a few sentences specifically to this hypothesis in the conclusion. That rape, while obviously atrocious, would have an evolutionary advantage for the reasons you cite should be fairly obvious. While this theory certainly seems plausible, I'd definitely be wary of when and how you bring it up. Foreskin and circumcision are already tense topics as it is without bringing rape into the dialogue. I have to admit that although I heard of this theory a couple years ago, I've avoided bringing it up (even in forums up to this point), because I don't want to come off as anti-foreskin.
For what it's worth, there are a few other theories I've heard for the evolutionary development of the human foreskin. One is that it is adhered to the glans tightly until puberty in order to lengthen the period during which females can develop before subjecting them to the risks of pregnancy and childbirth. Another theory is that the positioning of the foreskin at the tip of the penis, rather than the base, during sex, would make it good for scooping out the semen of reproductive competitors. Ironically, the flared glans of the circumcised penis has been proposed to possess the same reproductive advantage (although we're obviously talking about social, rather than biological evolution in that case).
Along those lines, perhaps one further theory that might interest you can be found in Leonard Schlain's book Sex, Time, and Power. He has an entire chapter in this book in which he describes his theory for why circumcision arose, despite it's relatively paltry benefits compared to risks (in a society conducting the practice with rudimentary tools, and at an older age when the blood vessels in the foreskin are more developed). Schlain basically suggests that it would have been the women of the community that would have embraced this tradition because of the improvement in sexual performance (at least for the woman) that circumcision provided. I would give you the caveat that, while Schlain's books are extremely interesting reads, he has a tendency to be pretty selective on the research that he presents; and it's always going to be the articles and books that support his theories.
I think that all of these theories have to be taken with a grain of salt. Let's be frank, none of them have much relevance in modern culture where we aren't trying to out-impregnate the next guy in a social system where everybody's fucking everybody. Still, as long as you're tactful about what audience you present it to, it could definitely make for some interesting cocktail party banter.