Make It Rain

Me, Myself & I Fat Joe
He means that the girl did the "Shoulder Lean" which is a dance, and a song by young dro. Hit me just means that she did it directed to him
Saying that he has a lot of money and is therefor "rainin game"
here we have an explanation of a self proclaimed "drug lord"...powder is the reference cocaine since it is white like baby powder... and the mention of kids is simply him "schooling" or teaching the fact that he deals cocaine and is the best at it~
I'm here in this place with my associates from our group The Terror Squad
Actually throwing money at women/hoes/strippers. When you throw a lot of bills over a women it looks like the money is [raining down on her]
I spend extravagantly on the many girls with whom I party
a "triple beam" is a type of balance (or scale) that has three beams along which you slide counter-weights to get a measurement. this is referring to using one to weigh bricks of drugs (probably cocaine) before sale, purchase, or dividing up.
Fat Joe is rapping with Lil Wayne, and he is saying his brother (friend) from the dirty (dirty south; Lil Wayne is from Louisiana) has a habit of drinking promethazine (prescription cough syrup).