William Medina and Claudia Luevano thought they were buying a cute outfit for their young son, Willie. Instead, they say, the talking shirt blurted an obscenity.

Their complaint has led Kmart Corp. to pull thousands of talking children's Cookie Monster T-shirts from 2,100 stores nationwide.The shirt has the Sesame Street character at the wheel of a dump truck filled with cookies, with a button children can push to hear the message, "Stand back. Here comes cookies. Mmmm, delicious."

Medina and Luevano said Thursday they heard an obscene phrase instead of "Stand back" on the $12.99 shirt and shorts set they bought Saturday for their 19-month-old son at a Denver store.

"I was showing everybody and they were saying it's the same word," Medina said.

Michelle Jasukaitis, a corporate spokeswoman at the company's Troy, Mich., headquarters, said officials listened to one of the shirts and couldn't make out any of the microchip message.

"We don't know what went wrong with the microchip on these T-shirts. We're looking into it. We have had no other problems with the other styles of talking Sesame Street T-shirts," she said.

She said the company pulled the sets "because of the nature of this concern." Customers can return the shirts to any Kmart for a full refund.

Kmart ordered 300,000 of the sets from Bentex in New York City and, after three weeks in the stores, about 150,000 are left, Jasukaitis said.

A Bentex receptionist said Thursday the company's spokesman was on vacation and unavailable for comment.