"The Space Suit Snatcher" is the tenth short story in Still More Tales to Give You Goosebumps.
A girl named Laura who is very interested in aliens goes to a garage sale, where the man who is running it, hears that she has a radio, which she uses to send messages to outer space, he becomes interested in her, and gives her a strange suit as a gift. When Laura's sister hears that she got the suit, she says that she is a geek, and is gullible.
That night Laura sends out on the nightly radio show she hosts (in the radio show she plays classical music, talks about earth, and then says peace to all in a different language), she receives a message broadcast to her. The message is apparently sent by aliens saying that they are going to come and get her.
The next day she tries to to tell her sister, but she does not believe her, and that night, Laura sees a alien at her window. She calls for her parents, but the alien disappears before they see it.
The next night is Halloween and when Laura goes trick-or-treating she sees the alien again, wearing her space suit, and this time it chases her until it reveals it is just her sister, who reveals her the whole encounter was a prank she pulled off with her friends. As soon as she is finished explaining how she pulled it off, she is suddenly transported by a real alien, who says by putting on the space suit her sister "volunteered" to join them. Before it leaves, the alien thanks Laura for her radio show, but suggests that she plays some rock and roll on it.