What is that old rap song with the piano in the background?

I am desperately trying to search this song but there is almost no
hope. I know everyone that listens to rap has heard this song at one
point or another.

But to be more descriptive:

- Theres a dude thats always saying in the background, "Up on it, up
on it, up on it "
- Theres a guy that is obviously rapping in a pretty fast pace, but
not as fast as busta rhymes or anything. Just a faster and more catchy
pace, and theres guys taking turns rapping at that same pace.
-Throughout most of the song, you hear a catchy piano beat that is
similar to what you would watch in a wild wild west movie at a saloon,
but it sounds cool. lol.
-You might hear this song in a radio mix, and thats where I heard it
earlier this week.
- I know this song isnt too old, but it is old, i beleive it is from
mid 2000's, not 90's music.