Funnily enough I had less trouble with the role playing in the air than the ground brief. I couldn't shake the sense that I was digging a big hole and my intructor was about to push me into it!
My biggest scary moment was during the ground school part where I had to stand up in front of everyone for a briefing. At that point the my future boss came in and stood at the back. He's a loud individual and I nearly melted. He threw in some pointed questions but in the end I parried him nicely and eventually sat down feeling like I'd got away with it.
After that, students were easy.