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