Top Three SQUIRREL! Moments in Lecture Classes

Yesterday's tale about an NYU prof reading the riot act to an entitled student got me thinking about the moments in my big lecture classes where I was flummoxed by unexpected behavior.  Sometimes I responded well, other times not so much.  Here are my top three (and please submit your own in the comments section) in chronological order--you can tell me which one is the most reeking of distraction sauce:

• It must have been the summer of 1997 or so at TTU--teaching a summer class in an era where cell phones only began to spread.  A student's phone rang, the kid answered it, got up and left the class to finish the phone call.  This had never happened in one of my classes before (or since).  I just stood there utterly shocked by this as were the students.  So, I told the students what I was thinking:
• "I have never had this happen before.  I guess because it used to be the case that the only people who had cell phones were drug dealers.  I am not saying this guy is a drug dealer.  Or that he isn't."
• So, they stared at him when he came back with the thought that he might be a drug dealer in their heads.

•   At McGill, I taught the big Intro to IR class to 600 plus students.  While nearly every McG student ends up taking a class in this room, I never understood why it was a standard stop on the tour of the campus.  Anyhow, I regularly noticed a tour group standing at one of the entrances at the top left entrance to this huge lecture hall.  They would stand there quietly and I would do my thing.  But one time, a group entered at the top right entrance and proceeded to walk through the class to the top left entrance/exit while I was lecturing.  I just could not believe my eyes that any undergrad guide could be so thoughtless.  Especially since the path they trod was in front of the last three rows of seats.  So, the tour group was walking thru the sightlines of the last rows.  
• My reaction was to do a running commentary on how wildly inappropriate this was.  I complained to the admissions department later on and they were abashed. 

• The third distraction was in the same lecture hall for the same course but a different year.  Some guy stood up to ask a question.  I didn't recognize him because, well, it is a big class.  So, I let him ask the question although no one really was in the habit of standing to ask questions in that class.  This guy then tried to profess his love for his girlfriend and to give her a gift.  I shut him down and told him to leave.  
• I regret not asking him to come to the front of the class so that I could take the gift from him.
• What I did do was track down the girlfriend since she had a rare first name.  I emailed her and suggested that her boyfriend showed a profound lack of judgment and that she ought to consider that in making any long term plans with this guy.  She mostly agreed as she was highly embarrassed and apologetic.

Of these three instances, I think I reacted best to the cell phone incident.  I made the guy look and eventually feel bad for being inconsiderate/rude and sent a message to the rest of the class that I will embarrass anyone who distracts a class.  Plus summer classes were longer so the three minutes or so were a pleasant break.  I think I managed the zealous boyfriend thing the worst--that I fell for his "question," that I didn't get his name, that I didn't steal his gift, etc.

So, what is your most distracting moment in class?