Ask HN: Where does “dead simple” come from?

I see the phrase "dead simple" show up all the time on GitHub READMEs and on Hacker News posts. Very curious where it originated, at least among programmers.

Found this thread on English Stackexchange, but it's not satisfying: https://english.stackexchange.com/questions/51593/where-does-the-phrase-dead-simple-originate

Are you getting saturated with this phrase, too? Do you know which project it originated from? Has it been around since Usenet times?