If you can't be the best, you can always be funny! And from that, the youngest child's personality is born. With size and smarts against them early in life, youngest children quickly learn low-power techniques like humor to carve a niche for themselves.
They're loved for being charming, affectionate, adventurous, and agreeable, but their tendency to be irresponsible, absentminded, impatient, and moody is less endearing.
Sacha Baron Cohen might want to thank his two older brothers for his over-the-top, risk-taking approach to comedy (he does interview a terrorist in Brüno).