Anything you want. There's no law saying what you can or cannot name a guinea pig. Some suggestions in order of (my) preference:
Oreo
Cookie (from the black and white cookie from Seinfeld. Ask your dad if you don't know what that is)
Dalmation
Fred
Spiderman (it's multipurpose, you can name anyone and anything spiderman and it works).
A black guinea pig would have a black coat color, while a white guinea pig would have a white coat color. Color variation in guinea pigs is due to different alleles of the gene controlling coat color, resulting in different phenotypes.
The black guinea pig is likely heterozygous (Bb) for coat color, while the white guinea pig is homozygous recessive (bb). The black guinea pig passes on a black allele to all offspring, resulting in 4 black (Bb) and 2 white (bb) offspring.
4 offsprings
Oreo would be a fitting name for a male guinea pig with those colors. This name reflects his white, black, orange, and brown fur combination in a playful and descriptive way.
Sooty
A single coloured guinea pig is called a self. (a guinea pig that is all black, white brown,etc)
A test cross with a homozygous recessive guinea pig (bb) would reveal the genotype of the black guinea pig. If all offspring are black, then the black guinea pig is most likely homozygous dominant (BB). If both black and white offspring are produced, then the black guinea pig is likely heterozygous (Bb).
Petri, a peanut butter colored guinea pig,Smorez, a black,white and peanut butter brown guinea pig,and Shadow, a black labradoodle. Note: These are from 2009 only
If a homozygous black guinea pig (BB) is crossed with a homozygous white guinea pig (bb), all offspring will inherit one black allele (B) from the black parent and one white allele (b) from the white parent, resulting in heterozygous offspring (Bb). Since black fur is dominant over white fur, all offspring will have black fur. Therefore, the probability of an offspring having black fur is 100%.
A Guinea Pig..
Well. I had a black guinea pig that had a white baby. It depends on her genetics. Their will probably be at least one white but no one knows exactly what the babies will look like.
I do not now if those are good names, (it depends on you) but you might want to name the guinea pigs a name relating to their color. My Guinea pig has a black face with a white stripe so I named her Blaze.