Also from southern UK and we called it knock down ginger. Looked it up and found this:
https://idiomorigins.org/origin/knock-down-ginger
Where ginger is to move "gingerly" i.e. cautiously or carefully. Can't comment on how valid that is but that website says the term has been in use since the 19th century.
Saturday is the only day of the week that has turd in it unfortunately.