HSOWA.....

This falls under the random category but I like this one better.

HSOWA is an acronym that stands for Hot Skitty On Wailord Action. It is derived from the fact that Skitty and Wailord can breed in the games despite the massive size difference. It has reached cult status on some message boards, such as GameFAQs and the Serebii.net forums.

The term originates from GameFAQs where, when this topic came up, the user Endgame reportedly said "HOT SKITTY ON WAILORD ACTION!". The name then stuck.

Strangely, though Skitty is quite small, another Pokémon in the same egg group as both Skitty and Wailord, Diglett, is even smaller, at 0'8". The reason that there is no HDOWA is possibly that Diglett and Wailord are not found in the wild in the same region, thereby only being together in the National Dex listing, not one of the regional Pokédex listings, as Skitty and Wailord are in the Hoenn Dex. Note that this can get even stranger with Seedot who, which is not only smaller then Skitty but based on a plant, can also breed with Wailord.

The reason why Wailord is included in the Ground egg group, the same group Skitty is in, in the first place is likely because whales are mammals, like most other Pokémon in the Ground group.

The only benefit from this is the baby Wailmer having the egg moves Double-Edge and Tickle.