Do you mean a gastroscopy, wolram? I have, and there's nothing to it. They sprayed my throat to make it numb, gave me an injection of Valium and something else, I nodded out for the majority of the procedure, and woke in a room where the hospital staff let me sleep it off. I didn't experience a sore throat or anything.
Some people -- such as my father -- remain awake regardless of the meds, but he was so calmed by the medication, he really didn't mind or care. I think he even got to watch a bit of what they were doing on the monitor.
It's not even a day-surgery thing. It's in and out in a few hours; just have someone to pick you up and cart you home.