The incident happened at a McDonald’s outlet in Derry, Northern Ireland.
38-year-old Lyn Richie (38), was at the restaurant with her 6-year-old daughter Ellyn. Reportedly, the child does not usually eat the burger buns, so she lifted the bun off her Big Mac burger and spotted the nail on top of the meat.
Ms. Richie alerted a member of staff and was swiftly offered a full refund.
She has now reportedly lodged an official complaint with McDonald’s about the incident.
In a statement released by the fast-food chain, it said: “We have begun an investigation following this incident and our Customer Service department will be in touch with Ms Ritchie to keep her updated,” the spokesperson added.
“Food safety and quality are our highest priority, and our restaurants and suppliers place great emphasis on quality control.”