Slow Mud ? - as opposed to Quicksand ?

This always goes through my head when I see this sign on the side of the road.
We all know what it means - it just needs punctuation and the words 'on the road' (or, better still, the road cleaned!)
I remember a hand-made sign on a farm gate some years ago - again no punctuation - just 'Budgies for sale free range eggs'. I had my Mum in the car, neither mentioned the sign but we both said simultaneously 'You'd need a lot for an omelette!'