Heh. I kinda figured it was a debug possible placeholder. I don't think it's a common, coder/programmer specific thing, as I personally have never heard of that specific phrase. But then again, I sort of haven't been up to speed on things in the coder/programming/hacker community. So if it's new, it's new(s) to me.
It is somewhat common practice to use random words as placeholders for variables and debugging stuff. Foo, bar or foobar are very common. When I was in school... heh, a majority of my debugging comments often involved colorful phrases such as:
This fucking thing doesn't work!
Fuckity, fuck, fuck fuck!
Frickfrackinfuck!
Shitty piece of shit!
And the like.
Kind of funny when you're working on a group project, and something craps out, and my partners see my debugging messages. lol. The majortiy of my classes, I almost always had solo projects, so I never had to worry about that before. Not exactly the most professional, but hey, it works, and it was good for a laugh.
Stupid string probably just refers to that, it's a stupid string.
I attempted to google this, and although I found a few references to stupid string, I don't think 'stupid string' is necessarily a specific phrase. Strings tend to just be stupid sometimes, especially a pain when it comes to trying to modify them. In some languages, strings aren't mutable (not easily manipulated) unless you use specific string functions.
As for in-game, I don't think I've personally witnessed this yet. But I have seen some debugging comments in Maxian code before with some funny messages.
Ste