Greet her

You swim closer to her, but she is so "busy", she does not notice you. As she cums from her intense masturbation, you decide to greet her to let her know you are right beside her.

Lily (with a grin): Hmm, so this is what you usually do, when not humiliating other publicly?

Julia (scared by the fact you were watching her): LILY! What are you doing here? How long have you been watching me...?

Lily: Hmm, just long enough to see you were really enjoying yourself!

Julia (with a red face): Fuck, now that is really embarrassing... But we are both girls and I am sure you have done similar things in the past too, so you understand it...

Lily: Don't worry, I understand, I did not mean to scare you, but sooner or later I had to let you know I was in the pool too!

Julia: At least you waited for me to finish, that was kind of you. Or did the sight turn you on and you couldn't bare to stop me huh?

Lily: That is not what I was implying...

Julia: A pity, I thought you were as horny as I was a few seconds ago... By masturbating you could have helped yourself get rid of some frustration...

Lily: No, I do not intend to do it...

Julia: But why? It is only us girls here!

Lily (as it is her time to get red): I won't do "it", while you are watching!

Julia: Why not?

Lily: I can't do it while being watched... That is it...

Julia: How about me lending you a hand... That would solve the part of "you doing it"...?

Lily: Weeell...