Interestingly, the people I hear throwing the word "gunner" around are just as bad, if not worse, than said "gunners" with their gossipy B.S. to put people down in an attempt to feel better about themselves, especially when done repeatedly, which if you're doing in your mid-20's is sad, grim, and pathetic.
You best bet:
Assume no one around you is a gunner. Don't call anyone a gunner, unless you're joking with a friend and you call them a gunner just as a joke if they studied the night before, because then it's funny when it's not serious. Otherwise, lighten up, grow up, and learn to like people for who they are. It takes some time, but slowly but surely, it works.
If you can't make that change in your mental mindset, you are in for 4 very long and painful years of drama and bullshiit.