I come across this a lot but haven’t succeeded in finding any good overview or explanation:
For some time, I’ve heard people add a syllable to the beginning or end of someone’s first name. It seems that /where/ the “a” is placed may depend on how it sounds with the name in question or maybe on the region the speaker is from.
This also seems to be something only done with friends and family where there is informality.
If your name is Chao, I might call for you or refer to you as “a-Chao” or “Chao-a”
Very recently, watching the addictive “Pretty Li Hui Zhen,” series, several of the characters are addressed by their intimates by taking the last character of their name and adding " 'er " to it. Ex:
Hui Zhen calls her BFF, Xia Qiao, “Qiao’er” who calls her “Zhen’er” - is this yet another way of “diminutizing” names or the actual PinYin for the “a” I’ve heard for much longer?