'Rub a dub dub' has to be one of the oldest nursery rhymes of all time, dating back to the 14th century.
The original lyrics refer to 'three maids in a tub' and it is thought to originate from the lascivious fairground attraction 'maids in a 'tub'' – akin to a modern peep show.
Thankfully by 1380 maids had been replaced with fools, and then by the 20th century it was the turn of the men to get in the tub.
'Rub a dub dub' lyrics
Rub-a-dub-dub, Three men in a tub, And who do you think they be? The butcher, the baker, the candlestick maker, And all of them out to sea.