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
Gwyneth Paltrow Pucci

And in Antonio Berardi, which is much racier. What shapely stems (and bootay) you have, Gwynnie!

Gwyneth Antonio Berardi
Jason Merritt, Getty Images
Gwyneth Antonio Berardi

Whoa! 'Thor' actress Jaimie Alexander isn't sidebumming it. She's onecheeking it.

Jaimie Alexander
Jason Merritt, Getty Images
Jaimie Alexander

Miley Cyrus shows off a hint of sidebum in this slinky LBD with cutouts.

Miley Cyrus
Christopher Polk, Getty Images
Miley Cyrus

See Zoe Saldana's perfect curve.

Zoe Saldana
Frazer Harrison, Getty Images
Zoe Saldana

Taylor Swift doesn't always show skin, but this is subtle sidebum.

Taylor Swift
Jason Merritt, Getty Images
Taylor Swift

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

Taylor Swift
Jason Merritt, Getty Images
Taylor Swift

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

Kate Winslet
Stephen Lovekin, Getty Images
Kate Winslet

Ashley Tisdale sparkles while she sidebums it!

Ashley Tisdale
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Ashley Tisdale

Kelly Rowland dares to sidebum in Georges Chakra.

Kelly Rowland
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Kelly Rowland

Selena Gomez's sidebum is red hot Reem Acra.

Selena Gomez
Christopher Polk, Getty Images
Selena Gomez

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

Julianne Hough
Kevin Winter, Getty Images
Julianne Hough

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

Jennifer Lopez
David Becker, Getty Images
Jennifer Lopez

That's Heidi Klum's back sidebum.

Heidi Klum
Charley Gallay, Getty Images
Heidi Klum

Here's the front view. Sideboob, too.

Heidi Klum Front
Frederick M. Brown, Getty Images
Heidi Klum Front

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

Kesha
Jeff Bottari, Getty Images
Kesha

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

Rihanna
Jason Merritt, Getty Images
Rihanna

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

Jessie J Sidebum
Andreas Rentz, Getty Images
Jessie J Sidebum

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

Jena Malone
Jason Merritt, Getty Images
Jena Malone

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

Kristen Stewart Sidebum
Michael Buckner, Getty Images
Kristen Stewart Sidebum

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

Kristyn Ritter
Valerie Macon, Getty Images
Kristyn Ritter

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