This is a lovely story in the Metro, that carries the headline, "Don’t worry you haven’t gone quackers – there WAS a giant rubber duck sailing down the Thames".  Yes, the story is about a giant 50ft rubber duck that took a trip down the Thames after setting sail from Canary Wharf. It was all a publicity stunt for an online bingo company.

To go crackers, means you go insane, and let's face it, if you saw a 50ft rubber ducky, you might question your sanity, but they have replaced "crackers" with the word "quackers".  Quack is the noise a duck makes.  Get it?

http://metro.co.uk/2012/12/11/giant-rubber-duck-sails-down-the-thames-3311508/