Miley Cyrus

Is my cousin in a gang, or is he just a "pretend" gangster?

Well, my cousin over the last year has taken a big turn for the worse. He’s in college (just turned 18 yrs old), and his 1st semester just finished and he has a 2.1 GPA. When he comes back home, he’s never here. He goes out till 4 a.m, got a $500 ticket for underage drinking, and my uncle recently found a large pocket knife that he carries around. His reasoning was “I need it, just in case.” He doesn’t listen to when anyone talks to him either. I also overheard him talking with friends and they were doing gang symbols and I saw him with a picture of all these different symbols on his laptop. He also talks about how he needs to get some tattoos, and when I ask him “why?” I’m told “it’s private.”
Where we live definently isn’t exactly a “rough area”, we live in suburbs, but it’s known that there is some gang in our town (I don’t know much about it).
What do you think? Is he involved in some type of gang, or is just pretending?