SoundToys is giving you the chance to get hold of a free vocal transforming pitch plugin known as Little AlterBoy. Said to be capable of pulling off all manner of classic vocal tricks - including hard tuning, octave DJ FX, robot voices, gender shifting and more - this will be available until the end of 1 April (and that's not a joke).
Rather than simply letting you download the effect, though, SoundToys is once again asking people to hunt down a redeem code that will give them access to it (the company employed the same strategy when it released its LittlePrimal Tap delay plugin in 2014).
The initial batch of codes was handed out at SoundToys' Plugged-In party at SXSW, and codes were then shared online. Everyone who registers a code gets not only their copy of Little AlterBoy, but also their own unique sharing code. Your 'score' then increases every time somebody registers that code, and those with the highest scores on 1 April will win prizes (first prize being free SoundToys plugins "for life").
You can find out more on the SoundToys website, but the bottom line is that finding a code shouldn't be too difficult. In fact, a 5-second search online should sort you out.
Little AlterBoy runs on Mac and PC and is VST/AU/AAX-native compatible. You'll need an iLok account in order to use it, though not the iLok hardware.