keep this a secret from everyone in class

(Class no Minna niwa Naisho dayo!)

References to a line (and/or her pose while saying the line) of Kaname Madoka's from episode 10 of Mahou Shoujo Madoka Magica. Madoka says this to Akemi Homura whilst she and Tomoe Mami battle the witch Izabel in one of the previous timelines.