President Hime realizing just who the "handsome masked cat" really is.
Any time Aika is startled and screams loud enough to send the birds scattering. It happens twice within minutes in one episode of The Natural.
President Aria went into an Alternate Universe of Aria. Everyone is genderswapped, but retained their original voice actors, even the guys. One might find it funny with the genderswapped Akatsuki and Woody.
When Cait Sith stamps Akari and President Aria's foreheads.
From the manga: When Akari meets Woody she rides with him on his sky bike to help him make deliveries. At the end of the chapter, Aika is talking with her about the, "Disgraceful Undine who was flashing her panties on a sky bike." Fast-forward a few chapters when Woody tries to explain to Akatsuki how he and Akari met when she yells out, "Woody-san, that's top secret!" followed by a tiny text of, "My panties..."