"Can I Get Your Number?"

I don't quite understand why someone men idiotic boys say "Can I get your number?" if they don't actually plan on calling. Do they like storing useless numbers in their phones? Because I thought that the purpose of cellphones and phone numbers is so that you can uh, call people? Silly silly. Don't get me wrong, I know that not all men are useless when it comes to their phones (I happen to know a hand full of great guys who use their phones accurately). But I can't help but question the majority. Good thing my new tactic is a simple and honest response "No (haha) No, no, I don't think so".