In the fable, to save the fox, a red herring (fish) was dragged across its path.
When the hunter's dogs reached this spot in the path the scent of the fish overpowered the fox's scent and turned them in the wrong direction.
This term is used today to describe the practice of intentionally planting false evidence in hopes of leading the police in the wrong direction; to distract them from the real evidence. It is also used to describe a tactic politicians use to distract their constituents from serious pressing issues, that the politician can't or won't address, by speaking passionately about some trivial but controversial issue.
What does this have to do with asking questions on JavaRanch?
When asking questions about code, or a software environment, it is easy to distract the people trying to help you by misrepresenting your code or by omitting important details.
A common example seen in the forums that deal with Java EE servers:
"I put my class files in myApp/web-inf/classes"
In a JEE application, the "WEB-INF" directory must be spelled with upper case letters.
If someone takes the time to point out this mistake to the original poster only to find out that, in the application server, the spelling was really "WEB-INF" but the original poster didn't care to hold down the caps-lock key when typing the question, that person will often become frustrated and stop looking to see what else may be causing the problem.