One day a blonde comes home from school and tells her mum that today they learnt the ABC's but she learnt the whole alphabet all the way down to Z. Her mum tells her that's because she's blonde.
The next day, her daughter comes home from school and tells her mum that today they learnt their 123's but she counted all the way up to 10. She asks her mother if this is because she's blonde and her mother says yes it is.
The following day her daughter goes to school and comes home and tells her mother that she has the biggest breasts in her class and she says to her mother "is this because i'm blonde?" to which her mother replies, "No dear, that's because you're 21"