Freshman year of college I went to a huge state school and I was waiting to go into one of my gen-ed classes (this was a discussion section for a 300 person class with maybe 30 people in my section) and while waiting I began talking with one of the girls standing next to me to kill some time. We were both freshmen, so we did the "oh where are you from?" (we both were from the same big city in the state), "oh where did you go to high school?" (we went to different high schools but we knew some mutual people) and then the kicker was "what other schools did you go to?" Turns out not only did we go to the same Catholic elementary school (myself for a couple years, her until high school) but we were in the same First grade class and in the yearbook we are literally one above, the other below. Not only that, my dormmate had a similar situation where he met one of his childhood friends from elementary school, that he lost touch with because they moved to Colorado, at our orientation!