Phoebe returns the comic book to Ross
Science Boy is a comic book created by Ross when he was a young boy. In his teens he was mugged by a "large boy" as he would say. His comic book and other possessions were stolen from him.
Later in his 30's, in "The One With The Mugging", he discovers that one of his best friends, Phoebe, was the thief. At first he does not believe her, but she grabs him by the ear and states the exact same words she said as a child. To help him forgive her, she brings his beloved comic to Central Perk and gives it back to Ross stating that she had learned a lot from the comic book.