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