The "Cougar Socks" bear the school's logo and team name, but have an unexpected message on the inside cuff: "Go Dawgs," the slogan of WSU's rivals, the University of Washington Huskies.
Strideline, based in Seattle, said the error was the result of someone on the design team failing to switch out the UW slogan for WSU's when the school's sock design was adapted for the Cougars.
"It's pretty unfortunate," co-founder Jake Director told the Seattle Times.
Director said it was only a coincidence that both he and co-founder Riley Goodman are UW graduates.
"We've got a bunch of Cougs on our team," he said. "It's not just a company of a bunch of Husky fans!"
Director said dissatisfied Cougars fans can contact the company for a replacement pair or gift cards.
Bartell Drugs said customers can return the socks to the store for refunds.