This question already has an answer here:
If two American strangers (or for that matter any nationals) are compatriot for each other What is equivalent of a person who is from the same college or university as yours?
See below example:
Somboon to Jim: Hi, Do you like the Philippines?
Jim to Somboon: Hi, we liked Philippines a lot. Jack and me are compatriots. We are US citizen. So we like to travel different countries.
Somboon to Jim: Oh you are from the same country, but you look different. I thought you are Filipino.
Jim to Somboon: No I am not. But Jack and me are in fact ___________ (from same college).