S3·E8 Principal from Another Planet

During a lunar eclipse, Principal Perry arrives at the house to inform everyone that aliens are on the planet, much to the cha Bree, Chase, and Donald's chagrin, but Adam and Leo's shock. She insists that Chase's upset stomach is due to an alien growing inside him and chases him. However, they notice green goop leaking out of Principal Perry's ears and mouth. Donald then admits that she's an alien. Principal Perry chases everyone, while Leo records the whole thing, and eventually tires herself out. Leo accidentally wakes her and she runs off with him to the school. Adam's heat vision destroys the alien pods Principal Perry laid and Leo is freed. The mother ship beams Principal Perry away just as Donald arrives. Thinking that they will miss Principal Perry, they are sadly mistaken when the mother ship beams alien-less Principal Perry back down. It is then revealed the whole thing was Leo's entrant in a contest.