I once found this in a c++ long method while searching for optimizable loops and unnecessary processes, it was a rendering update for a skeletal animated actor, the method itself was a good 150 lines long total and in the midst of its implementation there was this while loop:
//The following block of code should not be executed anymore, keeping it around for fallback reasons
while(0)
{
... do about 20 lines of stuff...
}
Seeing this actually hung my brain for about a minute before I yelled "Who the F* doesn't know how to comment a block of code on C++?" to the whole office.
The perpetrator was no longer working for the company and was responsible for many ridiculous pieces of code of which this was one of the last that didn't get deleted and fell through the cracks.
Granted, the code didn't actually get executed and the compiler likely did away with the whole loop, but it was still blasphemous.