The video for 2Pac's hit 'How Do You Want It' featured some pretty famous (at the time) porn stars.

According to one of them, Angel Kelly, Pac got his freak on with her -- and with Nina Hartley and Heather Hunter. [Jump to 15 minutes.]

Kelly said that it all started when Pac got turned on by Hartley's outfit.

"He's talking to Nina and her boyfriend, and of course Nina brought all of her whips and her little handcuffs and all of that kind of stuff.   Dominatrix stuff.  He was enthralled with all of that," Kelly.

Pac ended up having sex with Hartley while her boyfriend watched.

After that, Pac had a threesome with Kelly and Hunter.

Angel gave him good reports as a lover.