When Bart's birthday party turns into a disaster, he uses his AM radio gift to play pranks on the townspeople. Eventually he uses it to pretend to be a boy stuck in a well, and the whole town comes to his aid.
Homer: (Wearing glasses) The sum of the square roots of any two sides of an isosceles triangle is equal to the square root of the remaining side! Man: (From inside a bathroom stall.) That's a right triangle, you idiot! Homer: D'oh!