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