The co-writer of "Shock Me" from the '80s classic "Perfect" isn't exactly thrilled that his song got a spotlight in Jimmy Fallon's viral sketch with Jamie Lee Curtis -- telling TMZ he hasn't seen a dime for it!

Bruce Roberts tells TMZ he's pissed NBC didn’t clear the use of his song, and when he reached out to ask about it, he claims they hit him with the "it’s a parody" excuse -- meaning no license fee needed.

He’s calling BS, though, pointing out the 'Tonight Show' bit may have been parody, but the song was straight-up the real deal from the film.

Bruce didn’t hold back, telling us, "They basically said, ‘screw you,’ which only inflamed me more."

He tells us it’s not about the money, it’s about the principle. He’s fed up with writers getting stiffed when songs aren’t cleared, and he's not having it.

Bruce -- and Sony Pictures, which owns the master -- have been chasing NBC for answers for weeks ... but so far, they've been left on read.

Bruce ain't holding a grudge against Fallon, saying he knows him personally and doubts he even knows about the whole mess. He figures Jimmy’s just busy, and this is the kind of thing his staff usually handles.

Bottom line, he tells us he’s not a fan of lawsuits and is hoping this all gets sorted out before it even comes to that.

We've reached out to NBC ... so far, no word back.