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