Sideboob -- that's like so five minutes ago! It's sidebum that's become one of the biggest trends in fashion. The style, which shows just a flash of skin or of the butt cheek, has been on the rise for over a year now.

While it might seem as though sideboob is super scandalous, since it shows off a little too much and can lead to a nip slip, sidebum is even more terrifying, since it pretty much requires the wearer to go commando aka sans undies, since you can't really have pantylines with sidebum. And we all know what happens when said starlet gets out of a car!

Still, it remains a dangerous fashion "do."

Also, sidebum comes in all shapes, sizes and lengths. It can be just a hint, a slit, or a sexy flash of skin, covered by fabric. Or it can be a full on butt-baring look, where the air hits the flesh. The sidebum look often incorporates the thigh and the length of the leg, too.

There are so many varieties of sidebum! We've seen 'em all! The one constant is that sidebum shows off the shapely, round and curvaceous derriere in several sexified ways.

Repeat sidebum offender Gwyneth Paltrow in Pucci.

Gwyneth Paltrow Pucci
Frazer Harrison, Getty Images
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And in Antonio Berardi, which is much racier. What shapely stems (and bootay) you have, Gwynnie!

Gwyneth Antonio Berardi
Jason Merritt, Getty Images
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Whoa! 'Thor' actress Jaimie Alexander isn't sidebumming it. She's onecheeking it.

Jaimie Alexander
Jason Merritt, Getty Images
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Miley Cyrus shows off a hint of sidebum in this slinky LBD with cutouts.

Miley Cyrus
Christopher Polk, Getty Images
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See Zoe Saldana's perfect curve.

Zoe Saldana
Frazer Harrison, Getty Images
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Taylor Swift doesn't always show skin, but this is subtle sidebum.

Taylor Swift
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Upon closer inspection...it's more like an optical illusion created by two-toned fabric. It still counts.

Taylor Swift
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Kate Winslet's Stella McCartney frock is classic in its sidebum flash.

Kate Winslet
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Ashley Tisdale sparkles while she sidebums it!

Ashley Tisdale
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Kelly Rowland dares to sidebum in Georges Chakra.

Kelly Rowland
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Selena Gomez's sidebum is red hot Reem Acra.

Selena Gomez
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Julianne Hough stood out and not because her dress was neon in hue.

Julianne Hough
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With a bootay as famous as hers, J. Lo has to show sidebummage in Kaufman Franco.

Jennifer Lopez
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That's Heidi Klum's back sidebum.

Heidi Klum
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Here's the front view. Sideboob, too.

Heidi Klum Front
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Kesha's Givenchy LBD is really a LSBD aka little sidebum black dress.

Kesha
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Rihanna's sidebum was encased in a spiral-shaped Jean Paul Gaultier dress.

Rihanna
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A crimson concoction where the British singer Jessie J shows sidebum! Weeee!

Jessie J Sidebum
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Actress Jena Malone couldn't let this trend pass her by, thanks to her Nicholas Oakwell dress.

Jena Malone
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Bella got back! Kristen Stewart and her round rump...whoa!

Kristen Stewart Sidebum
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Kristyn Ritter rocked fishnet, but it was more like sidethigh.

Kristyn Ritter
Valerie Macon, Getty Images
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