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