Monkeybone.

After a car crash sends repressed cartoonist Stu into a coma, he and the mischievous Monkeybone, his hilarious alter-ego, wake up in a wacked-out waystation for lost souls. When Monkeybone takes over Stu's body and escapes to wreak havoc on the real world, Stu has to find a way to stop him before his sister pulls the plug on reality forever!