Dairy World is an unshown location in the Fairly Odd Parents universe.
Not much is known about Dairy World except that it exists. In A Mile In My Shoes, Timmy, trying to get to Fairy World to be a better Fairy Godparent, accidentally ends up in the wrong world twice, due to his inexperience with magic. During his brief trip to Hairy World, a high-voiced cow with wings, a crown, and a wand (all similar to that of a Fairy Godparent's equipment), also ends up in the same world, looking for Dairy World.
When Timmy does finally end up in Fairy World, he falls into a pit of volleyballs that he poofed up to break his fall (after Jorgen von Strangle removed his wings). After landing, the same cow shows up again, still looking for Dairy World.
At the end of the episode, Timmy returns home to Cosmo and Wanda, and the three agree to resume their original roles. Timmy tries to grant the wish, but instead turns the three of them into flying cows. The cow looking for Dairy World poofs into Timmy's room, notices cow-Timmy, cow-Cosmo, and cow-Wanda, and believes he has finally reached Dairy World, before being grabbed by Mr. Turner's Giant Fighting Robot to be used as a fuel supply for its "milk power engine."