This is a slightly different version of Rothbart's song, given a blues sort of feeling by the incredible Dr. John. It isn't included in the film itself, but is featured as a Bonus Track on the official soundtrack album.
Gosh, it's such a hoot to see them quaking
When I'm king they'll treat me with respect
And I can't wait to see their poor hearts breaking
So much for politically correct
Up 'til now I've pulled my punches
I intend to eat their lunches
No more Mr. Nice Guy, not for me
If you think that I'm hard-hearted
Well, let me by, I just got started
No more Mr. Nice Guy, no siree (no siree)
Vengeance is what I believe in
I don't get mad, I get even
As for the world, well that's tragic
I'm going back to that old black magic
Good behaviour is so much duller
Time to show my one true colour
Baby, Mr. Nice Guy's history
(I'm going back to that old black magic)
Up to no good, I love plottin' (he loves plottin')
Yeah, I'm so good when I'm rotten
No more Mr. Nice Guy, wait and see (wait and see)
I'll become that nasty, naughty, petty, spiteful
Wicked, wayward, way delightful
Bad guy I was born to be (you so bad, so bad)