At the hotel, where I realize I have forgotten a razor.
Me: Do you have a razor I can use?
SH: Do you think we should be sharing a razor?
Me: Is there something you need to tell me?
SH: I have a spare.
Me: Fine. Give it to me.
SH: But it's new!
Me: Then give me the old one.*
SH: But I'm not done with it!
Me: So what? Use the new one.
SH: I wasn't ready to start the new one.
Me: The total number of shaves does not change between us, you know.**
* This, by the way, is often our razor strategy at home. Legs don't need the same fine sharpness that faces do.
** Although now that I think about it, we are not optimizing total razor use if he doesn't use his razor as much as possible. I need to think about how to set up this formula.