Done when your gf or wife is wearing panties or more: Place your mouth on her crotch and slowly exhale. The heat from your breath will give her a nice warm feeling in her pussy, hence a 'hot kitty'.
My wife was sleeping on her side in the fetal position, so I gave her a hot kitty from behind.
Place your wide open mouth over your gf's underwear clad pussy (kitty). Exhale slowly. The heat from your breath will warm her nether regions, giving her a hot kitty.
My wife was sleeping on her side with her legs bent, so I gave her a hot kitty from behind and made her squirm.