Here's the deal ... SD appeared to host a sleepover at his place for Penelope and some friends Saturday night -- including her cousin, Kim Kardashian's daughter North West. The girls clearly take after their famous family members 'cause they filled their evening filming TikTok vids.

Disick's clip shows the girls filming his 11-year-old dancing down the stairs and through the massive Los Angeles-area estate. They're blaring "Murder on the Dancefloor" while PD twists and turns her way to the kitchen.

If all that sounds familiar to ya ... it's probably 'cause Barry Keoghan's character does the same thing in the movie "Saltburn" -- though he dances buck naked.

If you haven't seen the movie, spoilers ... basically, BK's character Oliver strips down and dances through the massive estate of another character's wealthy family after successfully murdering them for their money -- bottom line, very adult content.

To be fair, the dance has taken on a life of its own online with many people recreating it fully clothed, just like the girls did ... but it still had some fans online worried they may have seen the flick.

For the most part though ... followers on Disick's IG post are just lauding how fun of a time the girls look like they're having and applauding Scott -- seems like a lot of people think his house looks like a dang good time.

Penelope certainly seems excited about a girls' night in ... away from her brothers Mason, Reign and new baby bro Rocky who was born just a couple months ago.