Grillz

Sweatsuit Nelly
Nelly has a (bill)ion dollars worth of jewelery in his mouth. The reference to Hillary Rodham Clinton, who is married to Bill Clinton implies that Hillary would perform fellatio on Bill, having "Bill" in her mouth.
three6afix
3
Pun on the many carats in his grillz, thus the simile to follow.
Intellygentleman
5
when i exhale, my breath will move past my diamond-studded mouthpiece (or "grill"). diamonds are also called "ice" (they both sparkle), so he is jokingly saying this will change the weather (cause a cold front, because the ice would make his breath cold).
bill
4
his mouth is decked out with a grill, which is shiny and reflective and therefore resembles a disco ball
ms. d-dizzle
5
George Foreman sells grills that cook while eliminating a great deal of fat from meats. this is comparing his success to selling a different type of grill - a shiny mouth piece covered in precious stones/metals that you wear to be fashionable and show off
bill
4