péngyǒu jièshào biérén shí shuō “xiǎo chén”, nǐ jiù kěyǐ xiān jiào xiǎo chén

朋友介绍别人时说“小陈”，你就可以先叫小陈。

When a friend introduces someone as 'Xiao Chen', you can start by calling them Xiao Chen.