More than anything else, 13-year old Josh wants to be "big". That's the wish he makes to Zoltar, an odd-looking fortunetelling machine at an amusement park.

The next morning, Josh wakes up as a fully grown 30-year-old man (Tom Hanks), but still a 13-year-old mentally and emotions. Unable to explain this to his distraught mother who thinks he is his own abductor, Josh decides to hide out in New York City until he and his best firend Billy (Jared Rushton) can figure out what to do next.

There are some classic scenes from the film, my favourites being when Josh is checking out the products at the toy store, he impresses a Toy store owner with his childlike enthusiasm and they end up performing a duet of Chopsticks together on a giant foot-operated electronic keyboard; and when Josh and Billy are messing around and squirting silly string.

I remember there were several of these 'body swap' type movies around at the same time, "Like Father Like Son" and "Vice Versa", but neither of these were as convincing as Tom Hanks' character, who you could believe both physically and emotionally was a 13 year old in a body he's not yet used to or grown into.

The movie may be a touch predictable in parts, but it's genuinely funny and charming.  Much of the humour derives from Josh's inability to comprehend adult life rather than from childish innuendo. Much of its charm from the way Josh's innocence steadily revitalises those around him. This last point leads to a couple of cheesey moments, particularly the ending, but it's something you can live with as the cast barely put a foot wrong for rest of the film.