So we say Pigs might fly

In Israel it is When hairs grow on the palm of my hand

In France When chickens have teeth

In Finland When cows fly

In Hungary When the snowflakes are red

In Turkey When fish climb trees

In Spain When frogs grow hair

In China When the sun rises in the west

So no matter where you go there is an idiom for the unlilkely.

Today we have a confirmed date when our family will be together - breakfast on 4 Jan.  no pigs with wings/frogs with hair/climbing fish