Dexter's Laboratory - Season 2

Dexter is a boy genius with a secret laboratory hidden from the world, but keeping it that way is never easy. His curious and annoying sister Dee Dee keeps finding her way inside despite his best efforts to stop her, turning his experiments into chaos. At the same time, Dexter must deal with Mandark, his arch-rival and neighbor, as their ongoing competition adds to his daily misadventures.