Modern Art for Mugs
Superfrenchie's Oops! Entry and my own (much less spectacular) tea spillage incident recently caused me to realise I needed to wash my mug. However, the only implement in the office kitchen was a sponge of potentially dubious cleanliness.
The lack of implement turned out to be serendipitous - my attempt to clean the mug anyway meant my fingernails incised a design in the tannin layer. I could say that it just means my mug is still not very clean, but I prefer to claim that I have instead created some modern art in a mug!