  I hate it more than anything, yes even more than chewing noices when you go out to eat with someone and they talk on their cell phone.
It is obnoxious that you have to listen to their often boring one sided conversation, the rest of the dfellow diners do not want to listen to it and it is just rude. You are out with someone that that must enjoy your company enough to talk to you threw an entire meal, so why must you ignore then and let them sit there like a dumb ass. The people around you at the resteraunt are feeling sorry for the poor person that must not be interesting enough to get threw and entire dinner discussion that you must talk on your phone instead.
You might as well say to them "I am terribly sorry but you are boring me to death, so can you please sit there and be quit while I talk to a more interesting person on the phone" AHHHH it drives me nuts! There should be signs up that reminds these ignorant people that it is rude! Okay thanks for listening! 
