Dexter's Laboratory | Mandark's Sister | Cartoon Network

Mandark's sister Olga Astronomonov (a.k.a. Lalavava) tries to upstage Dee Dee at dance school. SUBSCRIBE ► http://bit.ly/2z61jDy Past the vaulted doors lives the smartest boy the world has ever seen, Dexter, boy genius! He's constantly creating dazzling, world-saving inventions in his secret laboratory. His big sister Dee Dee frequently wrecks his experiments. However, he has bigger problems such as his nemesis, Mandark, his brilliant rival at Huber Elementary School. Mom and Dad, of course, have no idea what their little angel is up to.