Kaia, or Kaya, means 'house' in the Nguni languages and, unfortunately, 'piccaninny kaia' or 'little house' was formerly used as the slang name for an outhouse - a toilet in its own little building, away from the farmhouse for hygienic reasons. The usual euphemism for it was PK - going to the loo and going to the PK were the same. (There was even a very right-wing white politician (in Southern Rhodesia as was) whose initials were PK. This made a lot of people very happy.)
Not a name I'd use, as you can imagine.