PepsiCo has engaged Lindsay Lohan to bring a naughty twist to a holiday tradition, encouraging consumers to mix Pepsi with milk and serve “Pilk & Cookies” for Santa.

The mix of milk and Pepsi—known as a “dirty soda”—is another example of brands seizing on a viral food and beverage trend on Tiktok. “Dirty soda” trended earlier this year on the video-sharing app, with users demonstrating combinations of soft drinks mixed with creamers, flavored syrups and fruits, showing Gen Z’s appetite for food “hacks” and customized products.

In another video, Lohan dons a Santa outfit and mixes the combination, pouring a Pepsi (“nice”) then milk (“naughty.”). Lohan stars in the new Netflix film “Falling for Christmas” and recently released a rendition of “Jingle Bell Rock,” associated with the film.

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The ads were prepared by Creators League Studio, which is PepsiCo’s in-house content agency.

Pepsi and milk has had a place in popular culture for years. It was a favorite of Laverne DeFazio of “Laverne & Shirley” and reportedly of Laverne actress Penny Marshall. The recent “dirty soda” trend has origins in Utah, where drive-through chains such as Swig and Sodalicious that specialize in such combinations were founded. Those chains benefited when the Mormon church in 2012 okayed caffeine in cold drinks and have now expanded regionally, becoming Mountain West competitors to chains like Sonic, which is also known for customizable drinks.

The trend’s crossover to viral social media was linked to an Instagram post picturing singer Olivia Rodrigo with a Swig cup.

Last month, the Larry H. Miller Company, owner of the Utah Jazz NBA team, acquired a majority stake in Swig, which bills itself as “Home of the Original Dirty Soda.” Miller said the company—currently with 46 locations in Utah, Arizona, Idaho, Oklahoma and Texas—has plans to open another 25 shops in 2023. 

Pepsi is promoting its “Pilk” with sweepstakes for fans who post their own photos of “Pilk and Cookies” on Twitter, Instagram or Tiktok, tag the @Pepsi account and include the hashtags #PilkandCookies and #Sweepstakes. Twenty-five winners will receive gift cards of $1,000.