Actually... With the right frame of mind and attitude, not only can you get away with it, but you can make a chick horny.
And I don't agree with the guys who think a girl must have been "easy" for the BJ to happen.
If you have beliefs like that, what are you doing on this site?
That's like going to a shop to buy a chocolate cake, while at the same time having the belief that chocolate makes cakes taste bad.
You're trying to pick up girls easily and effortlessly, while at the same time you have the belief that a girl who would give into sex/bj fast must have something wrong with her or it's a fluke.