Unlike the word "Ballz," the term Ballz and a half is both a derogetory and complementary interjection. It is used derogetorally to put more of an emphasis on a situations severity. In a good situation it is used as an expression of joy or excitment
If you were to spill you Dr. Pepper one would scream "Ballz and a half."
However if one were to comletely blow away some guy in a race, one would also sream this.