I am an uncle!.... anything my niece can call me by other than these names?
I am wanting to teach my niece some Japanese early on (Konnichiwa, nansai desuka, ones age, numbers, ojiisan, niisan, honorifics, you know basic stuff), so I was gunna have her call me something like "rykuu-nii" or "rykuu-jii" you know, something cute like that. But then again, if I go by "jii" it will make me sound old (I have yet to hit 21 years of age), and I am seeing if there are other things for her to call me other than some weird morph of nii-san.
So my question is, what other ways are there of saying Uncle in Japanese, and are there any other names/honorifics/nickname things that Japanese kids will use for Uncles?
Thanks in advance,