Cell Phones...rude? or not rude?

Since I work in retail I understand what its like trying to ask customers questions while they are ignoring you and talking on their cell phone...that's when I start talking louder or just stare at them.

This morning at the Buck I was standing in line when it was a gentleman's turn to order. He was quite engaged in his cell phone conversation that he had no clue what was going on around him. The lady right behind him, whom was making cell phone usage remarks to the rest of us in line, started ordering her coffee beans and drink of the day.....and at that moment the cell phone man started ordering his drink, while still on his phone...thats when the tennis match started. She was yelling at him, he was yelling back. It was fun to watch, I just wished I'd already had my coffee to make it more enjoyable.