I didn’t make that up. And some of the regional variations are far worse to modern ears. It’s the old celtic numerals - after a millennium or so of speaking english instead, and a traditional counting out “rhyme”. If you are counting real live sheep, you count each one and at the end of the series tie a knot in a piece of string. The number of knots at the end give you the number of sheep in multiples of 20. This is how you count sheep to fall asleep - recite the list in your head. Over and over.