Atrial Fibrillation

I heard atrial fibrillation for the first time while doing a physical exam today. I reviewed heart sounds on my own the night before (as we've never been lectured on abnormal heart sounds), but only the murmurs. Now I know that "holy crap, what is going on in there?" means atrial fibrillation. So that's what irregularly irregular sounds like! Ah, the power of learning by experience.