S2·E26 The Comet, the Unicorn and the Bad Gadgetinis

The unicorn comet approaches Earth for the first time in 777 years, which was also the last time unicorns were seen. The comet is putting out a magnetic field which affects electronics and Penny is worried her uncle might go haywire, but as the Gadgetinis say, how would you tell? Meanwhile, MAD's astronomer tells Dr. Claw that the comet's magnetic field also scrambles the natural invisibility field that unicorns can generate, which is why they're so rarely seen and why the last sightings were during the comet's last visit. Since unicorn milk is reputed to grant superhuman strength, Dr. Claw would like to find some to make his MAD agents superstrong. Back at Gadget's house, the Gadgetinis' programming has become corrupted and so have they, as they refuse to do any more work without substantial rewards. Dr Claw contacts them and promises them riches if they dispose of Gadget and catch him a unicorn and they agree.