The last post on sultry anthems focused on their role in the 15-year cultural excitement cycle -- announcing that girls are getting more comfortable coming out of their shell and are willing to engage the opposite sex again.
The feeling is no longer mellow, vulnerable, and withdrawn, as during the previous refractory phase. But it has not yet taken off on another manic spike. It's the restless warm-up phase, where people are transitioning from withdrawn and emo into hyper-social and invincible. They're doing warm-ups and exercises to wake themselves out of their slumber, to prepare for the real auto-pilot activity they will be doing when their energy levels spike soon.
Another aspect of that social mood is practicing flirting with each other, something they'd gotten rusty on during the emo refractory phase. They can be more spontaneous and let their guard down during their manic, invincible phase to come, but for right now, they have to spar with each other just to get back into fighting condition.
During the late 2000s, this manifested in the pickup artist phenomenon, and the accompanying female strategy of endlessly engaging in "witty banter" and shit-testing.
The natural musical form this social dynamic takes is a duet between two people who have just met, and are playfully teasing each other back and forth, usually in a call-and-response fashion. The lyrics are one line of banter after another. The rhythm is danceable, highlighting the mating-dance nature of the social setting.
These features distinguish them from other popular duet forms, such as those between couples who are already in a relationship. Those are either celebratory or melancholy in tone depending on the relationship's trajectory, and slower in tempo and lower in danceability, to suggest a couple simply embracing or looking at each other across the dinner table.
The playful banter duets pop up during each restless warm-up phase, the most recent one being the late 2000s. Several songs have elements of the form ("Hips Don't Lie," "Beep," "My Humps"), but the purest example of back-and-forth banter was already highlighted in the post on sultry anthems.
"Promiscuous" by Nelly Furtado & Timbaland (2006):
Before then, the last restless warm-up phase was the early '90s. An honorable mention goes to "Opposites Attract" by Paula Abdul, which is sung between an existing long-term couple, but does fit the rest of the criteria. Although not technically a duet since the performer raps both the male and female parts, with studio effects used to make his voice sound like a woman's, the main example from this period has some of the funniest lyrics of any rap song ever recorded, and is notable for the guy never catching a break with the girl.
"I Got a Man" by Positive K (1993):
The next restless warm-up phase before then was the late '70s disco era, although the clearest example of the form comes from a rock-oriented musical.
"You're the One That I Want" by John Travolta & Olivia Newton-John (1978):
During the early '60s, the next restless warm-up phase back in time, the same duo made two duets that fit the playful banter form. "Baby (You've Got What It Takes)" is the lesser, since it's not quite as energetic and suggestive of mating-dance rituals.
"A Rockin' Good Way (To Mess Around and Fall in Love)" by Dinah Washington & Brook Benton (1960):
And although I generally don't go back before the 1950s, for lack of a fine-grained intuition about the pre-rock era, the 15-year cycle does predict that we'd find a playful banter duet in the late '40s. Sure enough, it's probably the first one that comes to most people's minds, especially as the winter season approaches. A good theory turns up insights even where they're not expected.
"Baby It's Cold Outside" by Esther Williams & Ricardo Montalban (1949):