One of my friends had an internship in West Virginia and he came back with a bunch of fun comments in the local dialect, for example, at the end of a series of conditions intended to whittle out non-compliant conditions:
Personally, I pepper my code with whatever I'm reading at the time, for example, I just saw a comment of a particularly relevant XKCD Comic
Way back in the Ice Ages when I was writing applications for Windows, I remember there was one section of code in an app that was the epitome of unreadable, unmaintainable, unintelligible code. It had been written by a long-since-departed contractor and was a crucial piece of the system that just about everything needed to use. It was riddled with bugs, but all the other code did ridiculous and over-complicated gyrations to get around the bugs, rather than anyone braving trying to fix the noxious code.
The comment on that block (I've saved it -- the comment, not the code -- to this day):
Not in a comment, but I once ran across production code that essentially depended on that to work correctly. We received messages from a stock exchange with 1=buy and 2=sell, or something like that. The libraries we used transformed those into their own values--103 and 101 I believe.
Then one day I had to test a subset of the system in isolation. Where it had been exchange --> lib1 --> lib2 --> app, I changed it to simulator --> lib2 --> app. Everything broke. Horribly. After some digging I found out that all the simulated buys were being treated by the app as sells and vice versa. At first I freaked out, thinking we had a huge CF in production. After a moment I calmed down and realized that if that had been the case, there would have been screaming up and down the halls long ago.
After some digging, I found something like this:
So lib1 turned a buy into a sell, and lib2 turned it back into a buy, so that our app saw the semantics the exchange sent out, albeit via the scenic route. Two wrongs made a right and all was well, as long as we didn't try to separate lib1 from lib2, where the permanent crossing of the streams was the only thing that kept things working.