Why are the penguins flashing rainbow?

On Week 3 Day 6, while battling noise in Scramble Crossing, I started a fight with some penguins that were sparkling and glowing rainbow colors. The effect looked similar to a starman from Mario, only without the invincibility.

Why were these penguins sparkling and flashing rainbow colors?

_{Gameplay from Week 3 Day 6 walkthrough by ArcticViper}