Christmas Day at one family home in western Sydney this year was a flick of the wrist away from going horribly wrong, after a child found a sharp, rusty blade resembling "something from a prison" inside a bon-bon.

The McNeilage family was sitting down to lunch at Northmead on Monday afternoon when 11-year-old Bobby alerted the adults to what he had discovered after ripping his bon-bon in half with his older brother.

Bobby McNeilage, 11, discovered the blade inside a bonbon purchased from Woolworths.

"I pulled it out and I tipped it upside down to get it out onto the table," Bobby told Fairfax Media. "I noticed that it was a knife thing, so then I showed everybody else."

The "knife thing" was a large, sharp, rusty blade, wrapped in tape at one end. Did it scare him? "Kinda."