The King Doggy is a secret Legendary pet in Bubble Gum Simulator. It can be obtained by opening a Common Egg. The chance of hatching it is 1 in 100 million (0.000001%), or 1 in 50 million (0.000002%) with the Lucky Chancesgamepass.
Trivia
This pet is currently tied with Giant Robot and Godly Gem for having the lowest hatch chance in the game.
This is the second largest pet in the game, the largest being Isaac's Creation 2.0.