From AMLopedia
The blue dragons are breathin' fire came from when Liam and Adam were watching that Nickelodeon children's show Double Dare. It was a new version and the host was a guy with a really gay lisp. One of the teams names was "The Blue Dragons" and they were really doing well. The host wanted to express to the audience how well they were doing, so he exclaimed "The Blue Dragons.... are breathin fire!!!" AND NO ONE LAUGHED. So he had to weakly say "...sorry."