A short realisation...

Finally! We have at last worked out what DS2 has been singing for the last week! DS1 thought it was the theme tune to Totoro (late 80s japanese animation), I thought it sounded like the old hymn 'Immortal, Invisible..',   but it turns out it was the second two lines of the 'second verse' of Row, Row Row your boat i.e. '..if you see a crocodile, don't forget to scream!' - it was when he added the scream at the end that the penny finally dropped.

And you only have to re-read that the once to realise that while we may attempt the ordinary, it feels unlikely we'll ever achieve it   ;)