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