Close friends know.

Example:
We were just on a week-long beach house vacation with three other families. At some point, in the middle of the night, one of the moms knocked on our door and asked if they could have some ibuprofin. There was no question that I'd have several analgesics (in fact I have aspirin, ibuprofin, naproxin sodium and acetometiphin in the pharma section of the large FAK).

Later, on the beach, the question was "can we have some string?" not "do you have any string".

As we left, one car had a dead battery. Straight to me they came...can we use your jump-starter battery?