The correct time to blurt out "CRAP!!!" is not:
1. When you are trying to poke a needle through another person's flesh
2. When your instructor is on the other side of the patients bed
These things tend to be worse when combined, so if you do feel it is necessary to let your Tourettes take over it is best to make sure that either your instructor isn't in the room with you, or you are not in a patients room.
Further, although it may be amusing when the patient says "I don't know what her problem is, it isn't like you said SHIT!" try not to laugh too hard. Because then the teacher wants an explanation (which you can not give her due to the fact that you are laughing so hard that you can't catch your breath) and tends to get very upset.
Finally, when your instructor pulls you aside following such a fiasco as this, try to act contrite.Do not upset the teacher. She is grading you.