“While we’re out I need you to do this, this, that, this, this, and clean these.”
“I did all of that yesterday, when you asked me.  They’re still clean.”
“DON’T YOU LIE TO ME, THEY’RE FILTHY!”
“They’re clean, just look at them.  Shoot, they’re cleaner than most of the stuff you’ve ‘cleaned’ in the past few months.”
“BUT YOU’RE A TEENAGE BOY!  YOU’RE FILTHY AND YOU STINK, SO IT HAS TO BE CLEANED AGAIN!”
“One, I’m 22.  Two, I just showered.  Three, there’s a limit to how clean something can be, and how clean it should be kept.  Yes, my living space is dusty and not sparkling, but strangely enough I’m the one who almost never gets sick.  Having me obsessively clean every room I come in contact with because you think I’m unclean by merit of my gender and age will more likely make me sick than it will keep me healthy.  You’re not the one using the facilities, so let me keep them clean as I see fit.”