There is always always always a hoop you can give back. If you cant think of anything on the spot your emergency line is - ''say it again please?''
As i say, this is an emergency line and you have to take into consideration which frame you are adopting by projecting it. The frame you give yourself is you cant hear her. Which is fine once, but if you keep repeating it this frame becomes heavier, and your going to seem - well. Deaf.

Personally I would say to them ''say please''
if they have already asked politely and said please i would say ''please with a cherry on top?''

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V1V

these replies ae great! thanks guys. i've been goin out now hoping im gonna get asked just so i can test some of these out lol.

Lol. I can only say what was mentioned above is great.

Act as if you didn't hear her asking you to hold it and go 'Finally the drink's here. You're pretty slow for a waitress y'know. Give me one good reason to tip you.' smile&wink.
Would this work?

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Take me home, where the HBs roam.

I like that idea to approaching another girl while you've her drink. And you could open like "hi! I´ve that girl pursuing me to take me home, I just met her for 20 minutes, I just don´t know what I do". Think about it, you're making the drink´s girl competitive and despiting the new girl. Now you can choose one of them or attack both later...