Got a couple from my first year of med school:
Had this professor (actual physician) that would make a HUGE deal if you showed up late to class - embarrassed the crap out of people all the way to their seat. Usually people walked in, and stood there waiting for his reaction (the door made a loud noise so there was no sneaking in) Anyways, local schools started, and I had no idea. Ended up behind a school bus all the way to campus. Finally got to the door for class - alas, 2 minutes late. So, I did the only thing I knew how to do which was get the first word in. Opened the door, he turned, and before he could speak I said, "Good morning, Dr. XYZ" in the most enthusiastic way ever, turned, walked up the stairs, and to my seat. Pretty sure I broke the man because he smiled with his mouth open and didn't say anything to me. Whole class erupted in laughter. It isn't as funny to type about, but I guess its because you'd have to know the professor. He's the kind of guy that was in the parking lot yelling at you with a megaphone before a test.
Met one of my classmates girlfriend back in May - only been together for a couple months. Anyway, started conversing and she said that she was starting med school in July. Further on in the conversation, she said something along the lines of "I don't understand how you guys talk about school all the time. When its me, I'm going to leave school at school." Her boyfriend and I looked at her like she'd lost her mind. I said, "Well, you'll understand. School starts to consume every aspect of your life. There won't be much else to talk about." She responded, "Well i did my medical masters with them, so Ive pretty much already completed the first year of med school, so my first year will just be like a review." I didn't laugh in her face, but I thought that poor girl was going to have a tough time. Anyway, she ended up breaking up with my buddy because she "didn't have enough time to even sleep at night much less have a relationship." We laugh about that whole string of events from time to time.