@random is quite correct, "gata" is Spanish for cat.
Cat, in other words, pussy. :D
The joke here, the way I read it, is that "chupacabras" is the name of a fantastic beast that sucks the blood of cattle. "Chupacabras" literally means "goat sucker". "Chupagatas" then, a completely made-up word, is a play on chupacabras and means "cat sucker"... and could, I guess, be the name of some kind of bloodsucking beast that targets cats.
Or, if you read gata as pussy, then "chupagatas" could mean something like "one who performs oral sex acts on the female genitalia" which admittedly seems much more appropiate for our Kaoru. xD
(Because, let's face it, there's no way all she does with all those cute girls she seduces is kissing... amirite?)