See Saw Margery Daw

"See Saw Margery Daw" was an Earth nursery rhyme, the lyrics to which went as follows:
 * See Saw Margery Daw,
 * Johnny shall have a new master;
 * He shall have but a penny a day,
 * Because he can't work any faster.

In 2540, Jo Grant recited this rhyme (along with "Mary Had a Little Lamb" and "Humpty Dumpty") to counter the effects of the Master's hypnotism, claiming that, by filling her mind with nonsense, she couldn't be hypnotised. (TV: Frontier in Space)