Just talk to them about it, calmly and respectfully. Let them know you love it when they come over, but because you have to pay for this place and your own food, you'd appreciate it if they were just a little bit more aware. Its most likely they don't know that some of their behavior is bothering you. Talk to them about it so they know how you feel. If they continue to disrespect you, maybe suggest you guys hang out at a different place--their places of residence, the library, a student lounge at your college/university, coffee shop, etc. Those are places they might not be able to be as loud--and they definitely can't abuse your stuff! Talk to them and see if that fixes the situation. If they are really your friends, they wil respect your space and listen when you talk to them. Good luck!
Boys Town National Hotline