Before the latest tush tease trickled down to the masses, it started with celebrities during this year's über-sparkly, über-mesh, über-nude-colored red-carpet season.
Then in early June, Rihanna took it to the next level when she accepted the Council of Fashion Designers of America Fashion Icon of the Year award all darned-near-full-monty in a see-through, sparkling sheath by her go-to designer, Adam Selman.
Rihanna "was feeding into a bigger cultural movement that is about being more daring and living for the moment," said Jeetendr Sehdev, a celebrity branding expert based in Los Angeles. "These young celebrities are not asking permission anymore to embrace their sexuality."
Off the red carpet, Kim Kardashian both wowed and repulsed fans last fall when she posted on Instagram post-baby pictures of herself wearing a very high-cut, one-piece, white bathing suit.
The pic spurred a hailstorm of posterior selfies still popping up on the social media site.
I have mixed feelings about all of this booty, booty, booty. The prude in me thinks these celebrities are setting awful examples for impressionable women (young and old), who don't have much selfie-discretion.
Yet my free-spirit side wants to cheer them on for bravely wearing sheer dresses, or shorts a few inches shorter than what's expected - especially when you see so many men trying to defend their catcalling and disrespectful commentary based on these women's clothes, or lack thereof.
"From a women's-studies perspective, you can't regulate what women can wear because that is all about controlling her sexuality," said Anthea Butler, religion and African American studies professor at the University of Pennsylvania. Still, she said, it's a shame that some women are trading on their bodies. "It's like, 'Damn. That's all y'all got?' "
Women aren't the only ones in Hollywood showing off their derrieres. Omari Hardwick's character, James St. Patrick, in the Starz glitzy series Power, regularly bares his butt.
And all of the male vampires and shape-shifters on HBO's True Blood give us an eyeful. (There is a reason Joe Manganiello - True Blood's sexiest werewolf, Alcide - was named Hollywood's hottest bachelor in People magazine on newsstands this week.)
But celebrities' rendezvous with the rear end is hardly new. Josephine Baker - who, coincidentally, was the inspiration for Rihanna's now-infamous gown - was known in the 1930s for her revealing costumes.
In the 1970s, singers from Barbra Streisand to Diana Ross commanded many a stage in sheer gowns. In the '80s, you could count on Cher to expose her backside. And in 1991 - more than 20 years before Miley showed us her junk in flesh-toned hot pants - Prince performed in bottomless britches at MTV's Video Music Awards.
The difference is that back then, nudity was much more of an art form. Today, after Jennifer Lopez started us on a two-decade appreciation of the bottom-heavy silhouette, celebrities are on a my-cheeks-trump-your-cheeks mission never seen before. Did you see Serena Williams' backside Instagram shot taken last month after she crashed a beach wedding?
"Everyone just wants to be talked about," said Jaimie Hilfiger, a Miami-based style commentator and fashion insider. Hilfiger was at the Miami concert where Beyoncé debuted her famous onesie.
"Everyone wants to be trending. Everyone wants a hashtag. Everyone wants to be talked about forever - which in this climate, is more than two days."
The rear reveals, Sehdev said, help fans see celebs as more transparent, so to speak, willing to share their most intimate parts with the public. Not to mention that "it's a testament to their hard work," he added - as in, working out.
Maybe. Butt-workout videos like P90X and Insanity continue to be popular. Yet the American Association of Plastic Surgeons is reporting that Brazilian butt lifts - a procedure that plumps the backside with the patient's own fat - have increased 16 percent from 2012 to 2013.
"The tight bottom is all the focus right now," said Kathy L. Rumer, a plastic surgeon in Ardmore. "It's fashion-driven. It's celebrity-driven. Women want Brazilians. Guys want higher, tighter butts. All races and ages are coming in."