Ragnar-O's

Ragnar-O's is a dungeon & raids achievement earned for defeating Ragnaros while three Living Meteors are ignited by Lava Wave.

Trivia
This achievement's name is a reference to Wowhead user TheCheat54's comment on the A Binding Contract page on Sep. 6, 2011, stating "I want to eat Sulfuras. It would go well with a fresh bowl of Ragnar-O's."  This in turn refers to one of the contract's terms, stating that the Thorium Brotherhood is not responsible if the signee was harmed by attempting to eat Sulfuras, Hand of Ragnaros.

The comment inspired an image of a Ragnaros-themed breakfast cereal that began making its rounds on the internet the very next day.