Kendall Jenner and a pal dressed as the ubiquitous Halloween pair Karl Lagerfeld and his cat Choupette last night at sis Kylie's party at Bootsy Bellows in Hollywood. Come on, guys -- the Karl costume's a bit played out at this point!

Tyga accessorized his scary costume with Yeezy Desert Storm boots (that's what we call 'em, anyway). And Kylie was so stealth, she managed to avoid the flashes of our cameras. But we did get a look at her costumes on Instagram -- a snow princess and then a quick change into Xena, Warrior Princess. Oh, and then there's a very ghoulish King Kylie in Tyga's new music video for the single "Dope'd Up" ...

So just where were sisters Kourtney and Kim on Halloween? Well, Kourtney was dressing up as a superhero with her kids Mason, Penelope and Reign and Kim was dressing up as ... herself! The reality star wore the floral dress she donned for the 2013 Met Costume Gala back when she was pregnant with Nori. Cute!

The day before, the sisters were all hard at work -- at the studio filming scenes for Keeping Up With the Kardashians. Kylie and Kourtney were in matching sweatshirt-as-dress/thigh-high boot combos, which we LOVE. And both have the bangin' bods to pull it off. Show off those thigh-gaps, ladies!

Meanwhile, Kim dressed her baby bump in monochromatic grey -- surprise, surprise. But if you find a formula that works, then work it!