St. Patrick’s Day falls on a Sunday this year—but it wouldn’t have, were it not for this pesky Leap Year.

That’s the premise behind an elaborate campaign from Jameson Irish Whiskey to celebrate Saturday, March 16 as “St Patrick’s Eve.”

The brand recruited "Saturday Night Live" performers Colin Jost and Michael Che to appear in a series of comedic ads and videos that broke on Monday over out-of-home, digital, social and connected TV platforms. The videos show how Jost and Che conceive of the holiday, then go about preparing to celebrate it.

On March 16, the brand will light up the Las Vegas Sphere in Jameson green; wrap ferries and water taxis traveling in the green-dyed Chicago River; and do a digital takeover of L.A. Live. In New York, Jost and Che will host a St. Patrick’s Eve party including a “rock drop” (the New Year’s Eve ball drop, but on “on the rocks”) with a surprise DJ guest. Consumers aged 21+ can enter for a chance to win a trip to the party at JamesonSPE.com.

In addition, the brand designed limited-edition St. Patrick’s Eve jackets in collaboration with Jeff Staple’s Reed Art Department. The $150 green jackets feature an array of brand-related patches (cocktail glasses, jigger, logos) and an inside pocket for a hip flask—which is also included. All proceeds from the sale of jackets will benefit the Restaurant Workers Community Foundation.

The last Saturday St. Patrick’s Day occurred in 2018. The next won’t arrive until 2029.

“Our ‘Must be a Jameson’ campaign honors a community anchored by their shared lighthearted spirit, so when Leap Year skipped over a Saturday St. Patrick’s Day, we did exactly what a Jameson would do: we created a completely new holiday so people can start celebrating St. Patrick’s Day a little early,” said Johan Radojewski, VP of marketing, Jameson Irish Whiskey.

Pernod Ricard-owned Jameson is also using the event to launch a new ready-to-drink cocktail—the Jameson Orange Spritz. The canned cocktail, inspired by Jameson Orange, contains 7% alcohol-by-volume, as compared to 5%-6% in the brand’s other RTDs, Ginger & Lime and Lemonade.