If he was that stupid he wouldn’t know you were actually supposed to put something in there.
I will never forget the guy who came into the shop after he had poured a quart of oil into his windshield washer fluid reservoir and wanted us to clean it out.
I opened the hood, took one look and told the guy it would be cheaper for him to buy a new one and have me put it in for him.
He declined that so I spent three hours at a $90 an hour labor rate cleaning it out and flushing the lines. It was a mess and the plastic reservoir had an offset filler neck so I couldn’t get anything down into the bottom corners to wipe it out. Fill it with hot soapy water,close the lid, shake it up, dump it out and repeat over and over and over again. It wound up costing him twice as much as a new reservoir plus installation would have.
Come see us again soon, moron.