When a woman asks you if or accuses you of being a playboy this is a shit test.

She's testing to see how you respond and whether you will become uncomfortable and/or obviously lie to her by pleading with her to believe that you're not.

You see, by accusing you of being a playboy this gives her an easy way to eliminate you. "I can't date that guy, he's a playboy".

So how do you handle this? There are a few ways. One of the ultimate ways to pass this kind of shit test when a girl accuses you of being something is to say:

What do you like about _______ so much?

-OR-

What turns you on so much about ______?

For example:

Her: You're a playboy
You: What do you like about playboys so much?

Her: You're short.
You: What turns you on about short men so much?

Another way to handle it is to tell her straight:

Look, I just met you and already you're trying to marry me. Relax, are you always so uptight?

In the above example, you reframe the whole situation as her being uptight, but you could also imply that she has some ulterior(and less than noble) motive.

Her: What's your job?
You: Oh...you're one of those girls who's only into guys for their money.

If you're dating several girls and she accuses you of having a girlfriend, asks if you have a girlfriend or asks you HOW MANY girlfriends you have:

Her: You have a girlfriend, don't you?
You: I have 3(or however many) girlfriends, but I'm looking for number 4. I think you could be number 4.
Her: I don't want to be number 4(or I want to be number 1)
You: We'll maybe you can be number 3. Can you cook?

Do this only if she's shit testing you. If she's just asking an honest question and you don't have a girlfriend say no, but remember that most people consider any girl you're sleeping with to be your girlfriend so it often makes it EASIER if you call them your girlfriends.

Remember that all of these must be delivered in a fun way.  Mock seriousness, for exmaple, works well.