Workers at over 100 unionized Starbucks stores around the US walked off the job on Thursday, coinciding with Starbucks’ Red Cup Day, a promotional day where customers receive a free red reusable holiday Starbucks cup when they order a holiday seasonal beverage.

The union says it is striking to protest the retaliation against union supporters nationwide. It is also protesting what it characterizes as the company’s refusal to bargain with the union on a first labor deal. There are 264 stores that have voted in favor of union representation. But no contracts have been negotiated even at stores that voted nearly a year ago.

The union is calling its strike a “Red Cup Rebellion” and is handing out red Starbucks Workers United union cups to customers instead. “This is to show them we’re not playing around,” said Tyler Keeling, a 26-year-old union supporter who has worked at a Starbucks in Lakewood, California — near Los Angeles — for the last six years. “We’re done with their anti-union retaliation and them walking away from bargaining.”