After GHB I feel that I am loosening up. How does that work?

GHB inhibits activity in the brain, just like alcohol does. At a desired dose, this mainly removes some inhibitions. You feel looser, talking is easier and you become more assertive. If you take just a little too much, you have less control over your body and it becomes more difficult to behave normally. Then your consciousness decreases. You are less aware of your environment and you can pass out.

Be aware that your boundaries are blurred by GHB. Keep this in mind before having sex with someone and use a condom.