On the topic of phone numbers, I always get paranoid now when someone I just met who isn't clearly my friend asks for my phone number. I had some random person at a competition ask for it, and I was only okay with it because they asked everyone else in my group for theirs, too. Society has made me paranoid!
I feel like if someone was obviously flirting with me (hasn't happened yet), I would be totally oblivious and probably be excited because someone took the time to talk to me :3