A person whose native language is said to be English created the following sentence recently:
The grounds of appeal announced on Monday state Justice Sifris erred in not finding Mr Goldberg was wrong in failing to set aside the summonses.
A brisk debate sprung up as to whether the sentence contained five negatives or only four, but all the experts did agree that it sucked.
The sentence appeared in an article about an appeal by two Australian journalists who had been served with subpoenas requiring them to disclose sources. A magistrate (that's Mr. Goldberg) ruled that the subpoenas were proper, and on appeal the reviewing judge agreed. The sentence above was written in an effort to explain what happened next. If you follow all the twists and turns, it seems to lead to the right place, but "the journalists say the magistrate should have quashed the subpoenas" gets you there a lot faster.
To be fair to the reporters, they were probably just repeating what lawyers told them, but still.
Scientists operating the Large Hadron Collider reported last June that they had seen evidence of a sextuple negative, but said that if this did happen it lasted only a few fractions of a second before self-destructing.