The only two ENFs I have ever seen in real life are:
1. A girl I went streaking with in college was embarrassed at first. She kept covering herself and hunching over, which I have to admit looked pretty cute. I just said "Hey, you don't see me covering up anything!" and waved my junk around, after which she laughed and uncovered. Later she got really casual about nudity and would walk around naked in our co-op pretty frequently. What an amazing ass that girl had, too...
2. My freshman year of college, my friend was really drunk and pulled the curtain on a female friend of ours who was taking a shower (the dorm had co-ed bathrooms). She screamed and was really upset for days, and in general it wasn't very much of a turn-on...