It's just Pepe's eye.
Spoiler: why bother? (click to see content)
The whites of Pepe's eyes share the same color as the lightest color of his pants. This is why none of his in-game palettes do much outside of slightly tint them. So yes, for the sake of making it easier to color some pants, I am changing ONE PIXEL in every frame of animation for Pepe. Oh and also a few for his second winpose since his teeth sparkle colors share with his pants, and some for attacks where his electric attacks actually light him up in pants-colored highlights