Over a cup of wine the Greek says, "Well, we have the Parthenon."
Arching his eyebrows, the Roman replies, "We have the Flavian amphitheater."
The Greek retorts, "We Greeks gave birth to advanced mathematics"
The Roman, nodding agreement, says, "But we built the Roman Empire."
And so on and so on until the Greek comes up with what he thinks will end the discussion.
With a flourish of finality he says, "We invented sex!"
The Roman thinks for a moment and then replies, "Ah, yes, that is true, but it was us Romans who introduced it to women."