One time in around 2008 when I was in undergrad, I got facebook requested by a guy named David Liu (same name as me) who was going to a school many thousands of miles away, and I noticed that he had facebooked about 20-30 other David Liu's.

About 3-4 years later, I was in grad school, I meet this guy in person (he happened to be going to the same grad school), I recognize his name and face, and let him know that he facebooked me back then, and he got a chuckle out of it.