Re: don't want to get AIDS
Yes, it is dangerous to sleep around with people you don't know. I wouldn't recommend a one night stand with someone you meet at a bar for many reasons. The first is that you are probably both under the influence of alcohol which will hinder your decision making. The second is regret, you might not feel good about yourself afterwards and may regret what happened. The third is protection, even if you use condoms you still have that chance of getting HIV if the person has it. Especially through anal sex where you're susceptible to passing fluids other than semen (blood for instance if there's a tear).
It might seem like everyone's sleeping around but they're the ones who are at risk. My advice is to find that one person you really get to know. Make sure he's clean and advance from there. It's very risky in the gay dating scene just as it is in the straight scene.