La surprise

Fully transformed into a Super Saiyan Great Ape, Goku begins to attack Baby. It is clear that he is now stronger than Baby, but in his present state, he can't focus his mind on fighting. He goes on a rampage, destroying everything in sight, while Baby escapes to his tower (where the infected Bulma is) with his plan in motion: to lock on the Earth and transform into a Great Ape to destroy Goku. After the rampage, Goku is about to drink from the lake, but sees the Earth again and tries to run towards it. Standing on a mountaintop, Goku is reaching for the Earth, when Pan shows up. She tries to bring him to his senses, but he swats her away. Then she shows him a picture of their family and friends on a beach vacation, and combined with Pan's tears, this reminds Goku of who he is. He then transforms again. Goku is now at Super Saiyan 4 (adult). (Source: Wikipedia)