What can you name a black and white guinea pig?

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).