I have a favorite type of pencil. It's the Pentel Twist-Erase III with 0.9mm lead, preferably in black. I don't just like them, I hoard them. I have eight of them in a box hidden in the house, plus the one I use regularly. If I lose the one in current use, I'll take out a spare. If I find the one I've lost, I'll put the spare back. It's a good system.
N uses these pencils too, except he uses the 0.7mm ones (which I used to use--that's how we got them in the first place). At one point, he couldn't find any of his and wanted to break into my store. It's embarrassing in retrospect, but I had an emotional reaction and refused to let him have any. Even when I eventually conceded, I gave him the one dark blue one that I had.
I've hoarded them since high school. When we were in California, I found two packs of the 0.9mm version (totaling 4 pencils) unopened in my dresser. N claimed them as his, and I started fretting about how we were going to tell his pencils apart from my pencils, since each pack had one black and one blue.
In addition to the pencils themselves, I have spare erasers and lead for them that will last until doomsday. Come the apocalypse, or Pentel's bankruptcy, or the illegalization of mechanical pencils, I'll be prepared.