If you don’t do it, then I will do it.
Works for me.
You should do it, though.
[two hours pass, concluding the kid’s day off]

Did my mail order come in today?
Did you clean the catbox?
I thought you were going to clean it. So… did my stuff come in?
It might have, but I can’t think about that right now. Those poor cats. They actually need a clean box of poo.
But…
You could just wait until I get around to it. Or you could do it. That would be quicker.
[Five minutes later the deliveries are made. She gets her stuff while the cats mess up the fresh litter box. All is joy.]