Fun story about that: In Ruby 2.x, the version GitHub originally launched with, every object implemented the method `id`, which returned the object id (in 3.x, it was renamed to `object_id`). Every object had this id, ActiveRecord models, strings, floats, integers, booleans, etc. Some objects had fixed object ids, like `true.object_id #=> 20`, `false.object_id #=> 0`, `123.object_id #=> 247 (2n+1)`. The `object_id` for `nil` is `4`.

Yehuda Katz was the first external user of GitHub after the cofounders, so his github user id is `4`.

The way Rails works, if you want to look up a user record, you do it by id:

    author = comment.author
    user = User.find(author.id)

Similarly, when writing Facebook apps with Rails, when you'd hit that same bug you'd see Mark Zuckerbeg: https://www.facebook.com/profile.php?id=4

I love this story, makes me wonder how many other fun bugs on GitHub have been lost to time.

These are the fun anecdotes that make perusing comments here so worth it. Thanks for sharing!

This is too funny. Thanks for sharing this tidbit!