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