Like Dr. Jekyll, Klump invents a potion which releases an inner demon. Murphy plays Klump as a lonely, obese science professor.
Buddy is egotistical, loud, crude and a sleazy womanizer.
If Murphy is making fun of his once obnoxious celebrity image, it's a brave performance. Most of the sequences with Buddy are contemptuous, not funny, because he is so obvious and crude. Murphy's Klump, on the other hand, is a genuinely appealing person.