Sesame Street: Kids' Guide to Life: Telling the Truth (1997)

Telly feels left out when all the other kids at Gina's day care are going to the circus and lies that his uncle is a ringmaster. After Gina reads the story of "The Boy Who Cried Wolf," Elmo has a dream of the story where the boy learns his lesson. When Telly's uncle (Dennis Quaid) drops in for a surprise visit, Telly admits the truth.