My school doesn't have a "popular" group per se, but it did have it's own sectionalised cliques. People with similar backgrounds and interests tend to hang out with each other more. Also, the group you tend to prefer to hang with in your first year, will be the one you stay with until you graduate. There is little to no gravitation. That has it's benefits, but if you want to join a new group or meet someone new, they might not be as open to accepting or wanting to get to know you.
As for me, I hung out with the Caribbean intellectuals. They were pretty similar to me and we liked to keep to ourselves and focus on our goals. As much as I love them, we do have our flaws. We are like the slightly condescending, judgemental crew who does not suffer fools lightly. Because of that, like the OP said, I tend to keep all my online activities (reading manga, going on forums, etc.) a secret.