Dirty cups

Not so long ago, "in commemoration of the 75th anniversary of the discovery of penicillin — a happy accident in which rogue mold grew in a forgotten petri dish,  the Royal Society of Chemistry has asked its most unhygienic stakeholders to send in photos of their most disgusting, molded-over and crufted-up coffee cups."

Many people did so. You can see some of the most memorable cups here.

(Thanks to Mark Dionne for bringing this to our attention.)