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