Stranger Things [1] stars Millie Bobby Brown and Noah Schnapp might be connected to the Upside-Down [2] in the Netflix series [3], but they share an even more special (and far less scary [4]) bond off screen. The teens, who have previously given us glimpses of their adorable friendship [5], recently put each other to the test by taking the BFF Challenge on Noah's YouTube channel [6]. In the game, each person has to try to guess the other person's answer to a specific question. It's pretty impressive how well they know each other, but the best part of the video is how quickly they derail a conversation. Between Noah imitating Millie's accent and Millie smearing Sharpie on Noah's face, it's hard not to crack up watching them!