Strike each word out and repeat the sentence.
You just gave a reply that proved a double negative. To quote your new messiah, "come on man"
You don't understand what a double negative is. That would be two negatives per one subject (
not necessarily two negatives in the same sentence). In the sentence you just cited, there is only one negative employed per each subject. The first subject was "
Obama" and the first negative was the word "
never". The second subject was "
Russia" and the second negative was the word "
wasn't". Again, there was a subject present for each individual negative used. Another way to put it, the negative followed the subject (
and there was only one negative in use, per each subject). That was not a double negative. You are wrong.
An example of a double negative would be: "
The boy didn't do nothing wrong." In that case, you only have one subject (
the boy) and two negatives (
didn't and nothing). However, it would not be a double negative to say that "
The boy didn't do what they said wasn't right." It is acceptable to have two negatives in the same sentence. You just need each negative to follow it's own subject. In this example, the word "
wasn't" follows the subject "
they".