From NukeIt – http://www.nukeit.org/

Here’s a small bash script that you can use to grab your followers’ followers. It dumps them in to split lists of 1000 users each. Windows users use msys with curl – it will work.

Why bash? Why learn a new language when you already have the stuff to do it without a bunch of extra deps? Not to mention the extremely low chance some idiot will steal it, compile it, then sell it on BHW or ebay for a crapload of money …