Or the SQL classic:

    NULL = NULL

It's not true or false, ... it's NULL!

Making messages to nil be a no-op is certainly an "interesting" feature of Objective-C. It can make some code a lot more convenient to write, but it can also make certain bugs really difficult to track down.

After having done Swift for a while, I'm a big fan of using an option type so that "reference to object" is a different static type altogether from "reference to object, or nil."