Wow, a researcher from a German university sent me a survey about copying code from Stack Overflow — and not just randomly! Because they found a snippet in one of my repos.
So, SO answers are CC BY-SA licensed, which is terrible (you basically aren’t supposed to use it in BSD/MIT/ISC or CC0/Unlicense/WTFPL code!)
But that particular project was GPL licensed, which is compatible with Share Alike! And that’s particularly amazing — most of my projects are under Unlicense or ISC. I just decided to use the GPL for that one because it was an Android GUI app.