In the rich text editor:
@SpookyMocha
In a comment:
[SpookyMocha](https://chowlings.com/user/SpookyMocha)
For Names and Avatars:
In the rich text editor:
%SpookyMocha
In a comment:
[![SpookyMocha's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/SpookyMocha) [SpookyMocha](https://chowlings.com/user/SpookyMocha)