The cast of "Stranger Things" knows how to get their scare on! In a sneak peek at Wednesday's "The Tonight Show Starring Jimmy Fallon," Millie Bobby Brown, Gaten Matarazzo, Caleb McLaughlin, Noah Schnapp, Sadie Sink and Finn Wolfhard pose as wax figures at Madame Tussauds New York, giving some fans of the Netflix show the surprise of their life!