Bhad Bhabie just dropped the video for her new single, "Bestie", featuring Kodak Black and it features a masked psycho killer clown. Turns out the man behind the mask ... is X.

Sources close to the music vid's production tell TMZ ... Danielle felt DMX was perfect for the part, and she loves shocking people with her cameo choices. We're told she reached out to DMX, and he was totally down to collab.

Danielle's only 15, so DMX had already released his biggest albums and starred in tons of movies before she was even born ... but we're told she still considers X one of her favorite artists.

As you know ... DMX just got released from prison, and he's been looking forward to getting back to work. We gotta say, it's nice to see him back in the music scene.

If you're wondering why Kodak's absent from the vid ... we're told the rapper just couldn't find time to be on set.