I see the wilfully-clueless are out in force on this one. I really thought your questions weren't serious, as to normal people these things are self-evident by age 15. However, seeing as how you identify yourself with "pron", I realised you're serious and you actually don't have a clue about these things. All right, I've had too much caffeine today and I'm feeling generous, so here goes:

> why is it that women find the need to flaunt their "sexual characteristic" at a workplace party (or any party for that matter)?

Women, men, children - everyone likes attention. The best kind of attention for a sexually mature person is sexual attention from a person that they desire. To display yourself at your best and be appreciated by someone you like is one of the best feelings there is. Not that you would know anything about that, the best feeling you've had was while watching "pron".

> Is this behavior common among women of all cultures?

Yes (duh). In fact, it is also pervasive among animals and even insects. I know, I know, who'd have thought?

> Has it been common throughout the ages?

Yes (duh).

> Is it a result of women's peculiar biology or perhaps of another mysterious dynamics?

Only someone who calls themselves "pron" would think this is in any way peculiar. To not desire attention from the opposite sex (let's leave homosexuals out of this for now) would be extremely peculiar.

> Is this practice commonly regarded as pleasant among human females?

See answer #1. Being appreciated feels good. People like to feel good. You do the math, genius.

> And what is it exactly that they want if they hope to achieve it with this colorful behavior

Anything ranging from the momentary pleasure of being appreciated, to finding somebody to love and spend the rest of their life with.

> I once heard that human females may want a stable male partner to help rear their young;

You haven't heard the half of it, son. What human females ideally want is a man who will provide the best genes for their offspring and be the best provider. Such a combination being rather rare, often females try to secure a gene-donor and provider separately. Typically, maladjusted men like you, who are, to put it kindly, not attractive to women, end up in the role of provider, and the desirable men get to have their offspring raised by the clueless providers.

> is this "hula-hooping at a party" the best evolutionary strategy to obtain that goal?

Replace "hula-hooping at a party" with "showcasing their assets" and even you should be able to figure it out. Push up bras, high heels, corsets, hoop skirts, dancing, anything that tends to attract the attention of the opposite sex, helps to attract the best mate possible.

Any further questions? Although I don't even know why I'm trying at this point. Something about horses and water comes to mind.

EDIT to answer the question you added later:

> Also, males of lesser species often display their buttocks prominently to attract females. Is this accepted behavior among humans, too?

As a matter of fact, women love muscular legs and buttocks on a man. The far more common "massive upper body, scrawny legs" physique isn't nearly as attractive to women. Strong legs are an excellent indicator of overall strength and good genes; in many primitive tribes, people explicitly desire "strong legs" in a mate. Even in older English literature you'll often find statements like "the lines of his/her legs showed good breeding" and so on.

Displaying the bare buttocks would normally get a man put in jail, so not in public, no. However, many men do the second-best thing by wearing form-fitting clothing. And women love it. Not too tight, though, that tends to attract the wrong kind of attention.

> Is it common practice at GitHub?

I seriously doubt whether anyone at GitHub does the kind of training necessary to build strong legs and glutes, so I doubt it. However, you can see this behaviour on display in other environments, like the gym, the beach, etc.