I don't think I can, let alone do, project enough power in a casual setting to make anyone feel obliged to buy me the liquid of my choice, although I suppose it's possible I'm mistaken.
Refusing makes the guy look bad, unless he has a particularly adept response. The request becomes "buy me a drink, or go through status shenanigans to not look bad." That's not exactly obligation, but it is a form of social pressure.
Asking for $5 (well, probably $7-8 if it's not a beer) isn't exactly obligation, either. Is that a request you would make of both men and women? If not, why not? And how it is different to a request from a drink, other than the latter being wrapped up in more social frills (and combined with more social pressure)?
If anyone is saying "excuse me?" shouldn't it be the person being asked for the drink (aka $7)? The only problem is that if men make this response, they look bad, due to the context-specific social power differential.
Is that a request you would make of both men and women?
Yes, I said so elsewhere.
Followup to: Do you have High-Functioning Asperger's Syndrome?
LW reader Madbadger uses the metaphor of a GPU and a CPU in a desktop system to think about people with Asperger's Syndrome: general intelligence is like a CPU, being universal but only mediocre at any particular task, whereas the "social coprocessor" brainware in a Neurotypical brain is like a GPU: highly specialized but great at what it does. Neurotypical people are like computers with measly Pentium IV processors, but expensive Radeon HD 4890 GPUs. A High-functioning AS person is an Intel Core i7 Extreme Edition - with on-board graphics!
This analogy also covers the spectrum view of social/empathic abilities, you can think about having a weaker social coprocessor than average if you have some of the tendencies of AS but not others. You can even think of your score on the AQ Test as being like the Tom's Hardware Rating of your Coprocessor. (Lower numbers are better!).
If you lack that powerful social coprocessor, what can you do? Well, you'll have to run your social interactions "in software", i.e. explicitly reason through the complex human social game that most people play without ever really understanding. There are several tricks that a High-functioning AS person can use in this situation: