My Chinese Flatmates, and a Different Sort of Tragedy of the Commons.

It's well-known that when scarce goods are held collectively, and individuals can utilise them without individually paying for what they themselves use, people will often shirk their contribution to the group store, causing the proverbial "tragedy of the commons". However, in some cases, if people have strong disinclinations to be perceived as shirking, the opposite can happen, and non-optimal equilibria exist where people over-contribute to the store. A case study: my flat's kitchen's dishsoap.