"You see people who are 19 or 20 years old and they don't even know who The Who is. It's like, where have you been? Justin Timberlake? C'mon. Where are the roots?"

In this quote, Dustin Diamond is revealing his frustration with the younger generation's lack of understanding about timeless rock band The Who. He marvels and dissatisfied that people in their late teens or early twenties are not acquainted with this iconic band, and he concerns where they have been and what they have actually been listening to instead. By mentioning Justin Timberlake, a popular modern artist, Diamond is highlighting the stark contrast in between the music of today and the roots of rock and roll. He is stressing the significance of knowing and appreciating the history and origins of music.