Thats good actually ha.

I always deal with this request in a similar vein. As a rule of thumb I don't buy girls drinks unless I'm in a relationship with them or they're one of my dearest friends.

My standard response to 'Can you buy me a drink?' is as follows: Obviously, women hardly ever approach with this question, it normally comes 2-3 minutes into a set, if it comes at all.

HB: '*whatever shit was said before*so, Am I getting a drink?'
ME: *Slight laugh, not derisive, genuine.* Do you think you've earned one?'

Then I'll change the subject quickly and alter my body language so I'm slightly closed off to her. or better yet, take a sip of your own drink and do the same.

The HB will hardly ever answer the question and straight away it makes her feel the need to qualify herself to you. On top of that the slight change in Body language demonstrates that you can leave if she keeps up this bullshit. You're pretty much telling her off and threatening to deny her of your company.

I hope this has helped.