Since krellor answered the main question:
I feel like it would be useful to know exactly how much alcohol is in a can or a bottle.
- By volume: multiply ABV by the volume of the drink.
- By weight: do the maths above, and then multiply the result by 0.789 g/ml.
RL example: the beer in my fridge is 350ml, 4.7% ABV. Doing the maths this is roughly 16.5ml of alcohol, or 13.0g.
My most enforced boundary is likely "if I clearly told you «no», do not insist". Insisting further won't just piss me off, but also decrease the likelihood that you'll get what you're asking for.