A group of Katy's drag queens -- who performed with her for 'SNL's' final episode this season -- tried attending the official after-party at Rockefeller Center in NYC ... but were denied because they weren't on the list.
The band of 15 knew Katy could only have a few guests, so they understood.
As they walked away, 2 drag queens ran into Scarlett and 'SNL' cast member, Colin Jost -- whom she's reportedly seeing. Scarlett was on a mission, telling the group, "That's ridiculous! Everyone knows that drag queens should always get into a party -- come with us!"
And just like that ... the drag queens got in. Swish Swish.