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