Jason Russell's friends at the Invisible Children organization were definitely NOT amused by Jason Biggs' video spoof of Russell's naked meltdown ... and now, they're firing back.
As we previously reported, Biggs stripped down to his birthday suit at a Chicago news station Thursday ... in what appeared to be a parody of Russell's nude mental breakdown in San Diego earlier this month (below).
We called Invisible Children for comment ... and a rep simply told us, "Who's Jason Biggs? Was he famous once or something?"
So far, no comment from Biggs' people.