1. Talk in the car....HANG UP AND DRIVE!!!! It is so dangerous! At the least, use a hands-free device! They come free with the freakin' phone! Laws have been passed in other western countries; It's time they pass one here. Don't even get me started with texting and driving. But OHhh no, we wouldn't want to impinge on peoples' freedom to be retarded.
2. Answer in the movie theater. 'Nuff said?
3. Talk at the dinner table in a restaurant.
4. Interrupt a real, live, face-to-face discussion with a real live person to answer the cell phone with, "Hello? Oh, hi! ......Nothing, you?"
5. Forget to turn off the phone during work, meetings, and other public gatherings. I am really going to try hard at this one. I find it extremely annoying and rude.
Any you'd like to add?