Would like to know what the phrase/letters vvzz stands for (or even
just what significance it has) in China (if any).

as a chinese person, i don't think it has much meaning. but after
searching the websites, really many people use this as nick name. one
people told me that it's from "vvei zhu zhu", like feeding the piggy,
somehow she thought it's cute.

Maybe that relates somehow to a Chinese word or expression for blogs,
so that "feeding the piggy" could be a suggestion that one was
contributing to supplying the blow.

Just a wild idea ...