Photo Illustration by Thomas Levinson/The Daily Beast/Warner Bros/Universal PicturesLike a rose-colored mushroom cloud, Barbie and Oppenheimer have towered over the box office since their debut. Movie theaters, whose crowds have atrophied since COVID-19 wrested filmgoers out of cinemas and onto their couches, are suddenly packed. Guests are showing up in custom T-shirts, decked out in pink, or, best of all, in costumes that switch from black to pink, in honor of summer’s FOMO-fueled double featu