That’s the halloweeen costume.
You trigger the halloween easter eggs by buying all the halloween themed furniture and setting them up in your room.
With that, just sleep for a few nights.
Also there’s one in the dungeon at night if you have it.
Alright I've gotten most of the halloween stuff except for Chloe's witch costume, how do you get that one? Also thanks for the help
Chloe’s is technically not halloween.
So after meeting Alice and having some progress with Jessica.
You check Chloe’s room on a weekend morning.