I think you are being " shy " around these girls because their beauty brings out your own insecurities. you think " ah, this girl isn't so great looking, so she wont mind if I'm not perfect ether". Therefore, you are comfortable because you know she isn't perfect, so you don't have to be ether! However, a HB10 APPEARS to be perfect on the outside, and hence you feel more pressure to be perfect on the inside. This leaks out all over you in your apprehensive ways you worry about things you are saying to her, and what she thinks of you.
STEP 1) STOP BEING SO DAMNED INSECURE! Your not perfect. You never will be. Once you are happy with yourself, then you can be yourself around others. step 1 is much more difficult to do then step 2.
STEP 2) She has the appearance of perfection, but she isn't even CLOSE to perfection. I want you to really think about this one. She is just as close to perfection as you are. Logically speaking, perfection is the same thing as infinity, because it is unattainable. Hence, you are just as close as she is. What does all this mean? she is just a human being. You are just a human being.
relax and calm down brother.
Everything will be alright! just have fun, its not a job. You aren't getting paid to preform. You aren't going to get a gold medal for tapping that ass. No one is watching.