Some customers at a restaurant in a California casino got a rude surprise when they got their bill. But it wasn’t the amount charged for the food and drinks that shocked the patrons; it what was printed on the bill itself.

Near the top of the dinner bill for three friends at Chilly D’s Restaurant were the words, “Fat Girls.”

The incident occurred Dec. 6 at an eatery that’s part of the larger Cameo Casino Restaurant in Stockton, Calif., according to ABC News .

The bill lists charges for three tri-tips with fries and three sodas, for a total of $25.50. A bartender named Jeff had apparently typed in “Fat Girls” to keep track of their bill.

"I got the bill. I was looking at bill (and) I was like, 'Why does this receipt say 'fat girls?'" customer Christine Duran told ABC News.

When Duran complained to a manager, she said he "had like a smirk on his face, like it was funny but trying not to laugh."

Despite the insult, the manager still insisted Duran and her friends pay the bill, offering them a 25 percent discount and then a 50 percent discount. They declined both offers.

After Duran publicized the incident, Cameo Club Casino's Maggie Lewis posted an apology on Facebook.

Lewis said the insulting treatment Duran and her friends had received is "intolerable in our establishment."