|I'm very important and must take this. Gordon is calling.|
Some of us want to be at the lecture and have therefore shown the respect of switching our phones to silent, or better yet, off. It is not only disrespectful to the speaker, it is also disrespectful to everyone else at the lecture.
Texting or tweeting during the lecture should be a no-no as well. All fidgeting can be distracting. I was in a lecture last week where a woman was fanning herself (admittedly it was a bit hot but she was also wearing several layers of heavy clothing). When she had finally cooled off enough to stop fanning herself, she pulled out a nail file and started doing her nails. I felt a deep hatred that day my friends.
Just as bad is when you call someone and they say, "Can I call you back? I'm just in a meeting." Well if you're in a meeting, why the fuck did you answer your phone? Is everyone in the meeting taking calls? No? Just you then?