In college, I got to do some actual "crisis acting" like he mentioned.
Our theatre guild helped out the EMT program each semester by playing victims. I got to play an uncooperative drive-by victim with a sucking chest wound in my back. You should have seen the look on the students' faces when they asked me if I could tell them what happened, and I grabbed one of them by the front of his shirt, dragged his face about six inches from mine, and yelled, "I BEEN SHOT, YOU STUPID F^^^!!!"



I got to chew the scenery like a lunatic and abuse the hell out of them while they tried to assess me - the instructor told us not to pull any punches.
Even the instructor was impressed when I hyperventilated, voluntarily spiked my pulse and faked a seizure.
The lumps I got from accidentally slamming my head on the floor a few times were't quite as fake as the rest of it though.
( As an added complication I also have some fairly impressive scars, although none are from combat or surgery... As a baby I supposedly had really sharp nails and would constantly scratch myself really badly - thus, now as a heavyset guy I have a very impressive half-inch wide scar on either side of my stomach that stretches from the bottom of my rib cage to just above my hips, and looks like I had some kind of major abdominal surgery.)