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