Kanye West had everyone scratching their heads Wednesday ... after he posted a 2008 video of a butt-naked Pamela Anderson giving a birthday cake to the late Hugh Hefner.

The rapper uploaded the old footage to his Instagram Story, showing the former "Baywatch" actress serving Hef the cake on a silver tray during his 82nd Bday.

At one point, Hef — the Playboy magazine owner who died of natural causes in 2017 — wraps his arms around Pam as she kisses him and dances in her stilettos. Pam shared a connection with Hef ... she was the February 1990 Playboy Playmate of the Month.

Strangely, Kanye dubbed the words, "Hide Your Bitch," over the audio for the throwback clip. What all this means and why Kanye posted this video to his IG yesterday is anyone's guess. As you know, Kanye's very good at confusing the hell out of people.

As for Bianca ... Kanye's better half ... she was nowhere to be found in the IG post, but she has something in common with Pam in the video ... they both wear no clothes!