I have a Perl program that takes uploaded information and produces a webpage. Yesterday, a webpage ended up upside down!
Here is the link: http://110bridge.com/gr/012041787729c1.htm
I would suspect a once-in-a-million fluke except the same thing happened last week. If you look at the source code, it is like ǝɹoɔs ʇןnsǝɹ sʌ ןnʌ ɹןp pɹq That's presumably the code for upside down letters.
My program has been running daily for like 10 years without seeing this problem or anything remotely like it. If you think of the effort it would take to do that intentionally, it really can't be a bug. Even if something converted every symbol to that code, you still would have the symbols in the forward order -- it also had to reverse the order of the symbols.
I guess it is a practical joke by some hacker. If so, I like it. But it will get tiring if it happens again.