Why was Janet Jackson in this movie?

I never saw The Nutty Professor in it's entirety. What I saw (on cable) looked funny enough, but I didn't particularly care to rent it and see the whole thing.
So when I heard that a sequel was coming out I really didn't care either way. But once I started seeing the promos, I decided I had to see it.

But why was Janet Jackson in this movie?

Eddie Murphy is a very funny man. He has always been, and I guess will always be. Hell he even sang funny songs! Who can forget "My Girl Want's to Party All The Time"! What a knee-slapper!
Oh wait, that wasn't INTENDED as a joke. OOPS.
But seriously, Eddie Murphy kicks ass, and in this movie he kicks it repeatedly!

No but seriously, why is Janet Jackson in this movie?

Eddie Murphy plays Sherman Klump, as well as his bad boy inner-self, Buddy Love, and Sherman's mother, father, brother, and best of all, his Grandmother. "She" steals every scene she's in! Personally I hope her line, "Oh, I feel so vulnerable", becomes a catch phrase! I know I already use it at my job to further alienate myself from the so called "normal" people that work there.

I still have no idea why Janet Jackson is in this movie…

I guess the movie is a technological achievement, but I don't think it would have worked without Murphy. He's so funny, that I can look past the non-stop bathroom humor.
Without bathroom humor, this movie would probably be about forty five minutes long.
But hey, to each his own.
It's not a particularly good movie, but Murphy is funny enough to make it enjoyable, and Sherman is sweet enough to make you care, even if for the life of you, you can't figure out just what the hell Janet Jackson is doing in this movie!