“Dude, what’s with that water?”
“What do you mean?” I asked back, reaching for the bottle.
“Is that… Is there anything in the water?” He smiled to mask an unseemly suspicion.
“Nope, just water.” I shook the bottle dismissively.
He paused for a second, processing his options, and then said in a somewhat accusing tone, “But it’s yellow.”
He was partially correct. If you fill a plastic bottle with well water, and there are even just a few parts per million of iron in the water, or a few dozen as in our case, the bottle will turn slightly orange over time. Or yellow, depending on the room lighting and the accuracy of one’s color perception. I explained this, and he looked relieved, and said “Oh!” with rather more emphasis than I expected. I stared at him for a few seconds, and as realization dawned I said “You didn’t think —”
“What?” he said with less innocence than was genuine.
“You thought I was drinking my own pee!”