Khloe Kardashian is steaming mad at Joan Rivers for spoofing her sister's sex tape by doing a pretty hilarious rendition with Ray J ... so she bailed on co-hosting Joan's show at the last minute.
Khloe was scheduled to shoot Wednesday for Joan's E! show "Fashion Police," but sources close to production tell us ... Khloe pulled out .... hmmm, just like Ray J.
It's thrown Joan's show into panic mode -- probably to the satisfaction of Khloe -- because they have to scramble for a new co-host and re-do the script.
TMZ broke the story ... Joan filmed a comedy sketch with Ray J for her new WE tv show "Joan & Melissa: Joan Knows Best?" -- spoofing Ray J and Kim Kardashian's famous sex romp.
It's pretty hilarious ... but the Kardashians aren't laughing.