$.answer=42

There is a JavaScript object representing all of the Google Analytics state and functions. When this object is set up, they add the property "answer = 42" to it. Then, before making this object globally accessible at `window.ga`, they double check that `window.ga` does not yet exist or that `window.ga.answer` does not equal 42. If it already equals 42, then the initialization must have already happened (maybe the Analytics code was included twice?), and so it doesn't proceed to clobber that already-initialized global Analytics state. Checking that the `window.ga` variable doesn't exist is not quite enough, since other JavaScript on the page may have set that property for some reason (of course, this logic wouldn't work if other code on the page had simple set `window.ga.answer = 42`, but that's unlikely to happen by accident). As long as it looks like the initialization hasn't already run, then it goes ahead and does the initialization and makes the result globally accessible at that point.

tl;dr: It's not just a joke; it's actually used to make it less likely that other JavaScript on the page hasn't created a global variable called `ga` which may otherwise prevent the Analytics code from running.

[1] For those not in on the joke: http://en.wikipedia.org/wiki/42_(number)#The_Hitchhiker.27s_...

Even to check an instantiation ...

    $.answer = 42;

    $.N = function () {
    
        var a = O[gb];
    
        if (!a || 42 != a.answer) {

            O[gb] = $;

        }
    
    };
    
    $.N();