I have this habbit where....?

Is that called awkwardness? I'm kind of in the same situation as you are in. If I'm at school and I talk to someone that I'm not very close with, say a classmate, and have a general conversation with them, I would smile at them the whole time ,and laugh after every sentence either the person or I say! It makes me seem like I'm overjoyed for no reason, even on a Monday O.o and I only have about 4 friends that I can actually talk to normally out of my whole school so :/ yeah.

But hey, I guess it works out for me cause it gives me a great reputation. People find me interesting to talk to and they can tell me any situation they have and I wouldn't judge them, so I guess I shouldn't complain :)

I personally like people that overly laugh at jokes because you feel good around them if you can tell a joke without putting much thought into it and have the other person laugh a lot.

You're probably laughing out of nervousness. Maybe you need to see a neurologist to see if there are any treatment options available for you.