How many beans make 5?

It's a British sort of joke phrase such that when asked the reply or answer is:

Bean, bean, bean and a half, half a bean and a bean.

My father used to ask me this when I was young and it was told to me as,

"Two beans, a bean and a half, half a bean and a bean."

After looking at various sources trying to figure out why anyone started saying this at all, I came across many versions. They all seem to contain most of the following parts in some arrangement: two beans, a bean, bean and a half and half a bean. I decided on this version because if listen you can hear the rhythm like a poem.

"Bean, bean, bean and a half, half a bean and a bean."

Oddly about 1 in 5 of the answers didn't actually add up to 5 beans.

British term. A shibboleth designed to establish whether a person had learned nonsense rhyme "one bean ,two bean,a bean and a half and half a bean" from his Nanny and thereby establish upper or upper middle class origins.

Seedy sex game played in the bars of Pattaya, where a man guesses the age of a woman based on the view of her clitoris. Played as a best of 5.