You could call your close friends , by putting “阿”at the beginning , pick one character of your friend's name, then put “阿”before the character. It's like a nickname used between good friends.

It’s pretty similar to the Japanese word ～ちゃん, but not that intimate, 阿～is more like something between ちゃんand さん。much of the time, we call someone 阿～ when we are close enough to the person. However, in literatures, 阿～is also popularly used as names of characters.

Such as one of your friends called 张志远，you can call him 阿远 this is a kind of endearment,and remember that always use 阿plus name's last word to become 阿X