Ol'Line Rebel

I think you mean, EGD. It's not really a "test", but a literal examination of your insides. It stands for "esophagogastroduodenoscopy" (scope of the esophagus, stomach and duodenum), but is often simply called an endoscopy (which only means "inside scope", so really can mean any internal scope). The EGD is a tube put through your mouth and throat to view your esophagus, then stomach, then the duodenum (right after the stomach, 1st part of small intestines).