Giving a guy your number? Hell, it makes you look extremely desperate and slutty! If you were my daughter I'd spank your ass!
LOL... I'm just kidding. I'm the club jester, what do you expect. No, no, by all means give a guy your number. Take the initiative. You've living in the post-feminism age where women are as physically strong as men, therefore should be do everything a man does equally, including approaching men. So by all means, take a risk. If you get rejected...well then, now you know how crappy we men feel when we get turned down. Tally up and keep trying, sweetheart. Trust men, someone is going to yield to your delicious feminine advances eventually.
i don't think theresa rule saying you can't do that. if you like this guy and you feel he likes you, why not give him your number? they may find it as a compliment, especially if he is quiet and shy and too embarrassed toask for a number. I say.. go for it!