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