McDonald's sold 7.5 million of the Shrek glasses which have been recalled due to low levels of cadmium, a heavy metal identified as carcinogen, which could come off on the hands of the person holding the cup.

In return, McDonald's will pay customers $3.00 to return the glasses. The glasses were originally sold for $1.99 with a food purchase and $2.49 without a food purchase before the recall.

"It's highly unusual to see a company that executes a recall pay any premium over the regular price," said Don Mays, senior director of product safety for Consumer Reports.