"I decided to try it because I thought all of the TV shows were lies, but turns out I was wrong," Gavin said.
Karen Alexander, James' mother , said her son told her he got the idea from the movie, which is based on stories about a boy growing up in the northwest Indiana community of Hammond in the 1940s.
"I can't believe he did it, but they learned their lesson," she said.
James said he plans to eat a lot of ice cream to help nurse his wound.
"When you're young, you're just messing around," he said.
Billie Dempsey, Gavin's mom, said a nurse called them to tell them the boys' tongues were bleeding.
"The nurse asked them, 'OK, who double-dog dared who?"' Billie Dempsey said, a reference to a phrase that a character in the movie used to dare another child to stick his tongue to the pole.