Ray J -- There's a Right and a Wrong Way ... To F*** with a Kardashian

Ray J called out Tyga in a big way ... saying he's crossed the line messing with Kylie Jenner.

Ray and Princess Love were leaving Warwick in Hollywood Wednesday night when they announced their allegiance to Blac Chyna.

But the best part ... Mr. J explains the right and wrong way to cavort with a Kardashian.

He should know ... he's made millions off it.