S10E22 They Saved Lisa's Brain
LIsa is invited to join Springfield's MENSA group but,after they are chased out of their meeting place, they go to complain to Quimby. Fearing they have exposed his corruption he flees town. An ancient charter then reveals that in such cases the town should be ruled by the smartest people so the MENSA group take office. However,their elitist rules are very unpopular and Stephen Hawking has to intervene to save then from the mob.