I have to eat candies in 2's. Most particularly I have to eat M&M's, Reese's Pieces, Smarties, etc... (anything small and round) in 2's. If I get to the end of a package and there is only one left I will give it away or throw it away. I will not eat it.
Also, I made cookies the other day and I melted some chocolate chips to make little snadwiches out of them. I wound up with way more chocolate to spread than I actually needed. Once the cookies were done I looked at the leftover chocolate and couldn't throw it out. I considered my options and........I ate it.