I remember from schooldays (1950s/60s)

Ten bluebottles on a piece of meat.
Ten bluebottles on a piece of meat.
And if one bluebottle should wipe his dirty feet
There'd be Monday's dinner hardly fit to eat

Nine bluebottles on a piece of meat.
Nine bluebottles on a piece of meat.
And if one bluebottle should wipe his dirty feet
There'd be Tuesday's dinner hardly fit to eat

. . .