Well, I've tried entering the following:
-K (worked)
-Ki (worked)
-Kik (worked)
-Kiki (did not work)
-Kikiki (worked)
The only thing I can think of is if it is censoring it because it is similar to a swear in another language (however, I did check the censored words page and I could not find anything).
EDIT:
>More than likely, it is not allowed seeing as Kiki is similar to "kike", an offensive term used to refer to Jews.
commented 5 minutes ago by Sir_Mudkip