CALIFORNIA (KTXL) — Workers at 10 Starbucks stores in California went on strike Thursday, joining workers from at least 90 other locations across the country in protest of their employer’s response to unionization efforts, the union organizing the action said.

Starbucks Workers United, an affiliate of the Service Employees International Union, calls the strikes the “Red Cup Rebellion” in reference to Starbucks’ annual Red Cup Day promotion which also happens on Thursday, where stores give out free reusable cups with the purchase of a holiday drink.

The union produced its own red cups that feature the hand of Dr. Seuss’s The Grinch stealing a Christmas ornament.

The union accuses Starbucks of failing to bargain in good faith with workers who have voted to unionize.

“Starbucks’ continuous and lawless union busting has cast doubt on the future of the American labor movement,” Starbucks Workers United said. “If Starbucks can break the law to stamp out their workers’ unionization efforts, they could be writing the playbook for countless other companies to follow.”

The union said workers are on strike at the following locations in California:

  • 138 S Central Avenue, Los Angeles
  • 3241 Figurosa Street, Los Angeles
  • 131 E Katella Avenue, Anaheim
  • 3390 E. 7th Street, Longbeach
  • 4833 Candlewood Street, Lakewood
  • 1901 Mission Street, Sant Cruz
  • 745 Ocean Street, Santa Cruz
  • 1955 41st Avenue, Capitola
  • 4094 18th Street, San Francisco
  • 2843 Lenwood Road, Barstow

Baristas at a Starbucks in New York kicked off a wave of unionization efforts at other locations when they voted in favor of joining a union in January.

The first two Starbucks locations in California to unionize, which happened in May, are both participating in the strike.