Kylie Jenner and Sister Kendall Pose in Chic Dresses at Vodka Soda Drink Event

Kendall supported her sister at an event promoting Kylie's vodka soda drink Sprinter on Friday, May 10, in Las Vegas

Kylie Jenner and her sister Kendall Jenner are kicking off another hot-girl summer!

Kendall, 28, supported Kylie, 26, at an event at Marquee in Las Vegas promoting 818 Tequila and the Kylie Cosmetics founder's new vodka soda drink, Sprinter.

The dynamic duo proved that while at work, sometimes it's best to go back to style basics. Kendall wore a strapless little black dress to the event, as seen in a post on Kylie's Instagram account on Friday, May 10.

Related: Kendall Jenner Says She and Sister Kylie Jenner Never Competed: 'Biggest Thing We Would Fight Over Was the TV Remote'

Kylie stood out in a skin-tight red latex tank dress that hit below her knees.

"Sister work day @drinksprinter @drink818," the mom of two captioned a carousel post on Instagram that featured selfies with Kendall and a video of the sisters posing for photos in a space that appeared to be outdoors.

"Yep… You two are perfect," their older sister Khloé Kardashian commented on the post.

Related: Kylie Jenner Joined by Mom Kris Jenner and Sister Khloé Kardashian at Launch Party for New Vodka Soda Drink

As seen on Marquee's Instagram Stories on May 10, Kylie and Kendall worked as bartenders at the nightclub's summer kickoff event, and also spent time serving drinks and toasting with fans.

The laid-back event came just days after Kendall, Kylie and some of their sisters attended New York City's biggest fashion event — the annual Met Gala.

Kylie wore a pale pink Oscar de la Renta gown to the star-studded affair at New York City's Metropolitan Museum of Art on Monday, May 6. This year’s dress code was “The Garden of Time,” inspired by the “Sleeping Beauties: Reawakening Fashion” exhibit.

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Meanwhile, Kendall wore an Alexander McQueen fall 1999 look for Givenchy haute couture, sparking a debate online about whether she actually was the first-ever person to wear the look, as Vogue reported.

The model said that no "human" had ever worn the black gown, which featured beading and a scalloped back detail.

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