Caveat - IME it's mostly women doing the shaming, so if your friends are mostly male you might not see this trend.

I can't recall the topic ever coming up with my friends (more or less equal number of males and females) in the last couple years, so I don't know for sure about them. (From what little I can infer indirectly, the difference between the average male and the average female is less than differences within each gender, or between the average practising Catholic and the average atheist/agnostic/etc.) The friends I usually hang around with in high school (almost exclusively female, and almost exclusively non-religious) did seem to laugh at the promiscuous guy we knew slightly more good-heartedly than they did at the promiscuous girl we knew (though neither was anywhere near outright ostracised), but there were other differences between the two confusing the issue.

but experiments which did not involve explicit stating of values (like resume studies) find that people often hold prejudices that they claim not to hold.

What experiments? (Googling "resume studies" doesn't seem to turn up anything relevant -- "resume" is used as a verb in most of those results.) Anyway, I'm not sure we should care about prejudices people don't want to have (and sometimes aren't even fully aware of having), as per Yvain's "Real Preferences" post. (They might be consciously lying, but who does that on anonymous surveys?)