I guess I can try to explain it, although I'm not sure I can convey all of the nuances of it.
First of all, nobody (well...nobody that I know anyways) *actually* has a name like Wang Da Zhong.
Basically, a lot of overseas Chinese want their kids to learn how to speak Chinese, so, they send them to Chinese language classes every Saturday mornings.
Now, the curriculum is pretty standardized across the nation - at least I think it is, since I attended classes in both Seattle and Houston, and the textbooks were the same.
Obviously, little kids learning Chinese aren't going to know a whole lot of complicated words. So, the star of those Chinese language textbooks is called "Wang Da Zhong". All 3 of the words Wang, Da, and Zhong are pretty easy to write in Chinese.
Pretty much every lesson in those classes are conversations Wang Da Zhong has with other people.
For example, in one lesson he might be talking to his teacher. In another, his big sister. He might be doing various things, as he appears in a variety of situations.
As a result, Wang Da Zhong has gotten pretty infamous. I remember seeing a televised Chinese lesson on some Asian cable TV network, and they even got some Chinese kid to play the part of Wang Da Zhong, lol.
So, if you mention the name Wang Da Zhong to a second-generation Chinese living in the U.S., odds are they will probably know what you are talking about. It's kind of a running joke. Plus the name is just ridiculous