echo '127.0.0.1 news.ycombinator.com' | sudo tee -a /etc/hosts

Does the trick as well :) For bonus points (and so you can't workaround it with your phone), do it on your router/switch instead.

You'll still open new tabs and go to HN, but you'll be reminded quickly, and every day can be downtime day \o/ (for you, personally)