I also found typing "Fa.." became muscle memory. I found blocking it with /etc/hosts worked for me -

https://gist.github.com/thomasbilk/1506210/2d20f47bbcca75b2f...

[edit] I was thinking about redirecting to a google image search of cute animals wearing human clothes but after a few weeks of seeing 'this site can't be reached' my habit was successfully broken