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