<Table> <Tr> <Th_colspan="2"> "Rub - A-Dub - Dub" </Th> </Tr> <Tr> <Th_colspan="2"> Nursery rhyme </Th> </Tr> <Tr> <Th> Published </Th> <Td> 1798 </Td> </Tr> </Table> <Tr> <Th_colspan="2"> "Rub - A-Dub - Dub" </Th> </Tr> <Tr> <Th_colspan="2"> Nursery rhyme </Th> </Tr> <Tr> <Th> Published </Th> <Td> 1798 </Td> </Tr>

What is the meaning of rub a dub dub