Dave, your defense of diplomacy in social situations is astute but misses 
the real point of the joke, and why Kevin and I and other self-proclaimed 
feminists object to it so strongly.
  The joke contrasts women with (presumptively male) diplomats.  A diplomat 
always adds positive spin and pretends to agree to any proposal, whether 
they're actually agreeing or not.  A woman in her traditional role never 
explicitly acquiesces.	It should be obvious how dangerous that is -- 
implicit apologetics for rape, in fact, like Kevin pointed out.
  But even if you view it as purely a face-saving maneuver with no real 
ambiguity about consent [1], the underlying assumptions behind this 
gendered mode of interaction are highly troubling.  For example:
  * it is inappropriate for females to pursue a romantic interest
    (and the opposite for males)
  * it is inappropriate for females to be sexually active
    (and the opposite for males)
  * it is expected that females suppress their goals, desires,
    hopes, ambitions, and pursuits of happiness
    (and the opposite for males)

All of these undermine female equality!

OOH, check out the last 2 DON'Ts in this list from a 1950s home economics 
textbook:
   http://www.snopes.com/language/document/goodwife.htm#slave
     (the list at the top is fabricated or exaggerated; the do's and dont's
      list is real)


PS: In unrelated news, I was delighted to learn that today Washington 
state voted overwhelmingly in favor of a smoke-free workplace law.  A 
stronger one than any other state in fact, as it prohibits smoking even 
outside of bars and restaurants (so no outdoor smoking sections either). 
Almost all of Canada is already smoke-free (with Ontario's law taking 
effect in May) and it's clear the US is rapidly following suit.
http://ai.eecs.umich.edu/people/dreeves/whiteboard/smoke/


[1] Never having had sex without explicit bilateral yes's, I'm perhaps out 
of my depth here but it does seem like there would realistically be no 
such ambiguity regardless of the diplomatic conventions, but that's not 
the point.  None of us can relate to the mentality of a date-rapist.  If 
anyone can point to studies about a link between the "no means maybe" 
traditional gender role and rape, I'd be grateful.

-- 
http://ai.eecs.umich.edu/people/dreeves/improvetheworld

"Oh, forget it:  I can't write about this anymore until I find a
much more sarcastic typeface."	-- Bill Bickel