I didn't know what an iso was for 6 months. Everyone kept saying it so I knew it was common knowledge and I didn't want to look stupid by asking.
Oh my God, I think I have about 4,000 stories like this.
For lurking medical students and residents, if these posts resonate with you, I HIGHLY recommend this book:
I have searched high and low for something that answers fundamental questions that everyone seems to know but you're too afraid to ask, and I think this is one of the best that's out there right now.