Dries wanted to create a unifying symbol for the Drupal community. Something they could easily share and work with. Ultimately the concept took the form of 2 drops (ref to the name) put together to create an infinity symbol. When placed inside a filled circle, they looked like eyes, and the drop resembled a face. This way, the Druplicon was born: a stylized drop with "infinity" eyes, a curved nose, and a mischievous smile.
There's even a separate site for Druplicons from everyone who wants to create a new version. Have a look, it's really cool!