Jody Marks was buying dinner for herself and her husband when she says the cashier began gesturing at her chest and asking she had plastic surgery, ntnews.com.au reported.
When she didn't answer, the cashier repeated the question in front of several other people.
"I'd expect someone to say it to me at 2 in the morning outside a nightclub but not while I'm trying to get my dinner at McDonald's," Marks said.
When Marks and her husband complained to the manager, he suggested it wasn't a big deal, according to ntnews.
Eventually, Marks got in touch with the franchise owner and received free food. The company also apologized to her and said it was taking "appropriate actions" with the employee.