I went to some party with my friend and meet this girl. After i've been talking to her, dancing, and some making out, i wanted to get her number - I could, however, not remember her name.
I didn't feel like asking "hey whats your name again?" (since I already asked it twice, and didn't want to joke about it again). What I did to solve this problem was telling my friend to walk up to her with me, and introduce himself. He should then, shake her hand and ask for her name when introducing.
[Me, standing next to the girl and my friend]
Friend: Hi. I saw you meet my friend, what's your name?"
Her: Blah blah blah
Friend: Cool.
And it's as easy as that. At least if it comes to a situation that's common with that one.
Another one I've used to get the girls name a second time is, after a number close, handle your cellphone to her and telling her to enter the number on her own.
"Hey...take my phone and enter your number with your name in my phonebook."
Another thing to do is asking her for the number, write it on the cellphone, and then ask her what you should write as a name(ask in a c&f way).
She'll probably go something like;
"Just write my name"
If it's like the this you could just ask "Oh, so what's your whole name?".
She'll hopefully say her First name, middle name and then last name.
Once she says her first name you could interupt her gently and say "Oh I already know your first name." (Remember to be c&f).
Let her finish telling her the middle and last name, and then tell her that she got a cool middle name, and that you will enter her first and middle name in your phone to remember her.
Voila. Now you got it.
If you dont feel like doing anything like this you could just say:
"Hey... what's your name again?"