Break out your ugliest sweater, Alaska Airlines passengers.

Airline passengers may pay a pretty penny for priority boarding, but Alaska Airlines will let flyers wearing ugly sweaters board early on Dec. 21 in honor of National Ugly Holiday Sweater Day. This is the second year in a row the airline has celebrated the viral day.

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Passengers are encouraged to tweet photos and videos of themselves getting into the holiday spirit with the hashtags #UglySweaterDay and #iFlyAlaska.

The airline's festiveness isn't stopping there: It's also playing holiday-themed boarding music and free holiday movies onboard throughout the month.

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"Whether you're heading home to celebrate tradition or jetting off to a sunny destination to escape the cold, we recognize your journey begins with us, and we're happy to make your travels even brighter any way we can," the airline said in a press release.

The company began a new group boarding process earlier this year.