Whopper advert watchers told burgers contain cyanide and toenails as prank video backfires

People watching a viral Burger King video were informed that the burgers contain cyanide and toenail clipping as a prank advert backfired spectacularly.

The fast food chain launched a cheeky advert designed to activate digital helpers such as Google Home with the question "Hey Google, what's in a whopper?"

Bosses soon realised they had made a whopping mistake as tricksters rushed to edit the burger's Wikipedia page with claims that the burger's ingredients included toenails, rat meat and cyanide.

The entry is one of the top Google results for the search.

It also informed readers that the Whopper is the "the worst hamburger product" sold by Burger King.

The chain also faced some harsh criticism online for attempting to activate users' devices without their permission.

“When you take over someones phone or tablet and have it do your own remote commands intentionally, you are HACKING,” said one comment on the advert's YouTube page.

Burger King said in a statement that it was trying to undo the edits on the Whopper's Wikipedia page.

The latest version of the page appears to have the false ingredients removed but says it is "often at the center of advertising promotions, product tie-ins, and even corporate practical jokes and hoaxes".

According to reports Google appears to have reacted to the stunt by stopping its Home devices from responding to the advert's question - which may now be a relief for advertising bosses at Burger King.