Is there a canonical way to contact a GitHub user who doesn't appear to be involved in any discussions? For example, can you start a discussion on one of their projects to make a comment? From Anyway to contact a user on GitHub? I know I can alert the user by commenting on any discussion that they are involved in. But the user I'm seeking to annoy does not appear to be in any discussions (either that, or I don't know how to find his list of discussions). 
Contacting another GitHub user not already in any discussions
github
While there's no canonical way to contact a user, github recently introduced a Mention @anybody, they're notified feature.When you @mention a GitHub username anywhere in the context of an issue or pull request, that person is notified and subscribed to future updates.You can also create a gist & mention him in the comment, thereby notifying the user.