Being one of the youngest in both my EMT class and my medic class, I thought I would chime in here. There is no reason for them to be screwing around when it comes to learning how to appropriately do a patient assessment. We didn't have that problem for long in either one of my classes. In EMT school, day one we were put into groups and whoever was in our group was who we worked with. The instructor did a great job of meshing all of the various ages together in these groups. We had people ages 18-mid 30s in our class. One guy in my group had a hard time doing an assessment on me because I was the same age as his daughter. He quickly got over that on our first test day. Our program brought back former students who posed as patients and it went from "going through the motions" like we did in class on our clothed classmates, to actually having to perform a legit assessment and treat what we found...that included removing the clothes from our simulated patients. We had a few students that had to repeat the assessment station because they would not touch their patient, remove the necessary clothes, etc and they missed "fatal wounds" and had they not passed the retest, they would have been kicked out. This actually scared everyone into taking things more seriously, and the shyness issue went out the window. Another thing that it taught us was that we are probably never going to see our patients again (unless they are a frequent flyer, but that's another issue), so it didn't really matter if we were embarrassed or uncomfortable doing an assessment and removing clothes. Those that had a problem with physical contact with their classmates during an exercise got over it quickly knowing that they could fail out that easily and finally realizing that 1. your patient probably isn't going to care as long as you make them feel better in some way, and 2. that it's your license on the line if you miss something because you are shy, and 3. the first time you show up in the ER with a fully clothed patient that RN is going to kill you (our instructor worked in the ER and had some scary stories).
In medic school to get everyone to stop being stupid, we had to actually cut off the clothes of our classmates during assessment scenarios. We were all told day one to bring clothes we didn't mind getting ruined, and the girls were told to bring sports bras for lab days because we were all expected to play faking patient. And "affective domain" was a big part of our grade, so one smart ass comment or smirk during lab days and you would see it reflected in your grade. My point in this big long rant is, make these skills a big part of your student's grades. Do not let this behavior go on any longer. If that means pushing them and making them uncomfortable, then do it. They have to get over it sometime, and the classroom is supposed to be the place to do stupid stuff and make mistakes. They need to learn that now, rather than on a ride out with a preceptor who will chew them out for acting like that, or even worse, when they are actually out in the field working. No patient wants to be exposed, but sometimes there is nothing we can do about it. They expect us to be respectful and professional about it, and you should make it known that that is what you expect from your students.