if you're happy and you know it...

...do some really serious moves practise on the floor of the changing cubicle before you go to your first swimming class,
if you're happy and you know it, do some really serious moves practise on the floor of the changing cubicle before you go to your first swimming class,
if you're happy and you know it, and you really want to show it,
if you're happy and you know it, do some really serious moves practise on the floor of the changing cubicle before you go to your first swimming class.