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