I've heard of Sharp Cheddar, but...

PALM COAST, Fla. Oct 11, 2005 — A 16-year-old student bit into a razor blade while eating a chicken sandwich he purchased at his high school, authorities said. Craig Beat was not injured when he found the blade in his chicken patty Sept. 21, the Flagler County Sheriff's Office said.
Beat told school officials that he bought the sandwich at Flagler Palm Coast High School and sat down to eat it in the school's lunchroom, according to a sheriff's report.

Investigators did not know how the razor blade got into the sandwich. A spokeswoman for the Atlanta-based company that prepares and distributes the sandwiches said an internal investigation concluded that the razor blade must have been inserted into the chicken patty after it left the plant were it was cooked and frozen. No razors are used in the manufacturing process, and all food leaving the company's plants pass through metal detectors, said Gold Kist Inc. spokeswoman Karla Harvill. Gold Kist products have since been removed from all cafeterias in the school district, officials said.