A: [knocking on bathroom door] Can I come in?
A: Yes.
A: [enters] I’m going to brush my teeth.
A: …But I was going to brush my teeth!
A: But my toothbrush head is still on the Sonicare, so therefore I should do my teeth first.
A: …
A: It minimizes our collective effort — we only have to change the toothbrush head once between the two of us, instead of twice.
A: [dubious] Oh, I see.
A: It’s for the good of us all!
A: Uh-huh.
A: Who says only children aren’t altruistic?
A: Huh.