You Gotta Believe Me! is the 4th short story in More Tales to Give You Goosebumps.
Nobody believes Stanley's story. Stanley is trying to warn the world about aliens from outer space. Stanley isn't allowed to watch television, so instead he watches the skies. While watching the skies, Stanley sees flying saucers. He tries to tell his family about the spaceships, but they won't believe his stories. His sister Laura says he just wants attention, and his brother Dan says that he is a geek. Even Stanley's best friends, Robbie and Melanie, don't believe him, and neither does the police.
At around 11:00 one night, Stanley sees a flash of lightning. He uses his telescope to look at the light source. He sees that the light is coming from a flying saucer. The U.F.O. is floating above Mr. Tribble's cornfield. Stanley sneaks out to explore the field where the U.F.O. was. When Stanley gets there, the field is empty. Mr. Tribble comes out and yells at him. Stanley can't convince him that there was a flying saucer.
At around midnight the next night, Stanley sneaks out again. When he gets to Mr. Tribble's barn, he sees the flying saucer resting behind it. Stanley also sees green aliens on the ship. Stanley overhears the aliens talking. They reveal that they have been using television broadcasting to convince humans that space aliens aren't real. The aliens spot Stanley and catch him. The aliens force him to watch television for hours. The aliens think he is hypnotized, so they send him home. Stanley rushes home to tell his parents about the aliens, but they still don't believe him.
The next day, Stanley buys over $100 dollars worth of aluminum foil. He uses the foil to make a giant mirror. He puts his mirror in Mr. Tribble's yard. When the aliens come next, their spaceship shoots out a blue beam of light. The beam of light was meant to hit a broadcasting satellite, and inject its signals with the aliens' hypnotic messages. However, the light is reflected by Stanley's mirror back at them. The aliens are hit by their own hypnotism beam and fly away. Stanley assumes that they will be unable to return because they hypnotized themselves.
Without any real proof, Stanley can't validate his tale. The story ends with Stanley claiming that he sees the alien ship returning.