What is the name and artist hip-hop song about a booty bouncing...?

I am not sure of the exact words but it goes something like this:
She walking down the street and that booty go bum bump ba bum ba bum
ba bum
She walking up the stairs I see it go bum bump ba bum ba bum ba bum
bum

Any ideas who sings it and what it is called? I tried to look it up
but I don't know the exact words so it is difficult.
Thanks!