I think my friend might be gay/bi?

We're both 16 year old guys and go to high school together. I'm not gay or bi in case you needed to know, but everyday at school i talk to him and our group of friends. He acts completely normal around all them, but when the bell rings and we are walking in the hallway, he always grabs my hand for maybe 1 second and pulls away. He usually does it 1-4 times until we arrive at our class. I'm not even sure if he is just joking or not because he always says "big guy" every time he does it, which is an inside joke i guess. When i sit by him anywhere, he always ends up touching me somehow, whether it's with his legs, elbows, or hands. Sometimes when we are allowed to talk, he scoots his desk over to mine, but he does it in such a way that his butt is right in my face. He always laughs like he is joking, but he does all this stuff on a daily basis. Also, he gets really offended if I try walking in the hallways by myself or with another friend, be it a boy or girl. He gets mad at me if I try going to my 4th hour class without walking with him first, and he got mad at me today for doing just that. The last girlfriend he had was in 5th grade, and that was years ago. I have nothing against gay people, but it just gets annoying that he seems so clingy all the time. Can anybody clarify this a little better for me? I appreciate it.