OK, it's Saturday afternoon and I'm not gainfully occupied by SWMBO. I have just finished a book and then got to thinking, which is never a good thing.......... You know how sometimes you have a query, rather than a question, about 'something' - possibly how an object works, or what it is made of, or indeed why it even exists etc. Some time ago we had the white dog poo thread. So my thinking led me to begin this thread where the question can be asked and possibly a correct answer given. So, not only amusing but informative too! Let me open by asking: skidmarks - aka lumps of shit in a loo. How come a small (or large!) smear of shit on some shiny porcelain can dry so hard and so quickly in a cool damp environment?