Sheen Guerrero Estevez was one of Jimmy's closest friends and one of the main protagonists on the television series The Adventures of Jimmy Neutron: Boy Genius.
Sheen was one of Jimmy's best friends, along with Carl Wheezer. He was a person with a very energetic and unique personality and was seen as the wacky one of the group. He seemed more aware than the other Jimmy Neutron characters about how he's flatter in Timmy's world due to being 2D.
Sheen and Cosmo
In When Nerds Collide!, Sheen and Cosmo quickly took a liking to each other because of their similar personalities and ways of thinking. They worked together to create illogical wishes to get Jorgen angry enough to regain control of his body.