Mega-Boobs are from Mstrya, it is a Bad End, basically staying for too long at her torture chamber, while tied up Keep Waiting.
Again, Bad-End so do save if you plan to do it.
For the Saves on PC, just save your saves on a file as a Just In Case, disclaimer this is what I do when I mod games like Skyrim, or New Vegas, so it might not Work for this...