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