Obviously this would be to hand out to a girl when you strike up a conversation and connect on the fly.

For example, I think the cashier at my local grocers was flirting with me. I would find awkward to ask for her number, give my own, or stop the line to write stuff down. But if I have a pre-written slip in my wallet, I could just pass it to her.

But I guess my probably very silly concern is that she would think I hand my number to everyone and carry several slips of papers to hand out instead of making her feel special by writing it to her.

I suppose I could have stepped to my car and return with my number and pretend to have forgotten to buy something and then give it to her. Right? Lol