The Mask

Bride of Pretorius (1x7)

: 16, 1995

What REALLY happens in this episode is that Stan falls for a girl named Violet and invites her over. However she accidently gets the Mask on her face and becomes a female Mask bent on loving Stan. Pretorius kidnaps Stanley and has a plan to wipe out humanity finding Violet/Mask to be the perfect specimen for repopulating the world.