World Domination (or atleast less annoyance) via Cell Phones

An Annoying Situation That Could Be Solved by the Genious Marketers: Today I thought of a way to use an innovative marketing technique for my own personal benefit. Here's what happened.
On campus, I usually eat at a cafeteria that opens at 12. Since most classes start at 12:30, this leaves you only 30 minutes to order your food, have it cooked, eat it, and get to class on time. Today I was standing in line at noon wondering why they hadn't opened yet. They usually open a few minutes early, if not right on time. Then, I noticed all of the girls who work at the cafe sitting on the floor in the hallway that led to the cafe. They just sat there talking and laughing for five minutes. Finally, at about 12:05, they noticed me glaring at them and all stood up, but instead of coming over to help they went into a closet (with a glass window). All four girls stayed in there for an additional five minutes with every one of their cellphones open. They were showing each other text messages! By this time there were about 20 people in line and the cafe was supposed to have been open for ten minutes already. I was mad!
So here is my idea... One of the latest marketing techniques, which is mostly used in Europe for now, involves cell phone text advertisements. They can detect you cell phone within a certain range, like if you are in a subway station, and they send you a text message ad. I need this capability. I want a device that I can carry in my backpack that I just point at someone and it will detect their cell phone number and allow me to send them a text message. I would have sent every one of those girls a nasty little text message while they hid in the closet!
I think I'd also use it while driving in Utah. For those of you have never been been to Utah and don't understand the driving situation, imagine the busy traffic of California combined with the stupidity of cavemen (no offense to the popular Geico Cavemen). I would point my magical little device at every idiotic Utah driver that decides to run a red light and cut me off while talking on their cell phone. I would call them, give them a few carefully selected words, and tell them to hang up (Or I would instruct my passenger to do this for me... so that I wouldn't become one of those annoying cell phone drivers).