Any time there's an art shift, usually when Molester is feeling particularly emotional about something. Most notably the male waiter at the restaruant where the girls work at being drawn as Takakazu from Kuso Miso Technique and the recounting of the resolution to Miss Understanding's stalker problem done in the style of JoJo's Bizarre Adventure.
In chapter 18, Molester Man has a staff meeting with the sub-molesters in his brain. Molester A wears glasses and is serious, Molester B is cautious, Molester C is a coward, Molester D is obssessed with breasts, and Molester Lord is Sousuke Aizen. It must be seen to be believed.