Taylor Swift just made a congratulations video for newly crowned NBA MVP Russell Westbrook joking with the guy like they've been buddies for years -- even though they've never met.

The Oklahoma City Thunder star got the award Monday night -- and hours later, Taylor released the video saying, "Russell, it’s Taylor. Remember? I was the one who taught you how to play basketball?"

She jokes that she taught him everything he knows about basketball ... he gave her the idea for "Shake It Off" ... and that they go back 20 years.

She then admits they've actually never hung out together once.

Kinda funny. Kinda weird. Kinda sweet.

What's interesting ... Taylor really hasn't done any public interviews or appearances since February -- so this is sorta like her reintroduction to the spotlight. Who'da thunk she woulda used the NBA as a way in?