Big (1988)

A young boy makes a wish at a fairground machine to be big. He wakes up the following morning to find that his wish has been granted and his body has grown older over night. But he is still the same 12 year old kid on the inside. Now he must learn how to cope with the unfamiliar world of grown ups including getting a job, and having his first romantic encounter with a woman. What will he find out about this strange world?