By the way, instead of just linking to the Wikipedia entry, I have to quote a little bit of it for those who don't click away, because it's just too funny:
Chansey is a rare, egg-shaped, pink Pokémon with much fatty tissue along its sides, alongside hairlock-like outgrowths on its head. It is said to bring happiness and luck to whoever catches it (which is ironic considering the fact that Chansey is number 113, though, in Japan, 13 does not have the same significance it has in the United States). It has a pouch on its belly as a marsupial animal would, and in this pouch it always keeps a special egg. These eggs, several of which are laid daily by Chansey, are both nutritious and delicious to the point where they are eagerly consumed even by people who do not have an appetite.
Those eggs make up Chansey's "Softboiled" attack, which I love. I gotta catch one!