Ray J -- Serenades Kim Kardashian With Explicit 'I HIT IT FIRST' Lyrics

Ray J wants Kanye West to know ... when it comes to Kim Kardashian, Kanye's getting sloppy seconds ... because he hit it first.

As you know, Ray J famously had his way with Kim in the epic sex tape, "Kim K Superstar."

TMZ has obtained some of the hysterical lyrics to Ray J's new song, "I Hit It First," which will be released next week ... and they're awesome!

She might move on to rappers and ballplayers
But we all know I hit it first.

I had her head going North and her ass going South
But now baby chose to go West

No matter where she goes or who she knows
She still belongs in my bed.

We're told Ray J is making a music video featuring a Kim look-alike -- pre-pregnancy, we presume.