In first year at my university, people tended to seek out others who went to the same high school as them, whether they liked them or not, and re-form "(Insert Name Here) Class of 2012" cliques rather than trying to meet new people. There are like 35 000 undergrads at my school and people were trying to re-live grade 12. Two people I did not like AT ALL in high school followed me about for the entire year simply because OMG, I WAS IN THEIR CLASS. AUGH.
Now that we're all in third year and grown up, we've all made new friends in so many different places and "cliques" are certainly a thing of the past. Well, except for the frat boys and sorority girls, they seem to travel in large packs, consisting entirely of....other frat boys and sorority girls. I personally don't see the appeal, but for some people it's a way to form lifelong friendships.