A Bloomberg news service article cites DCist (specifically, Catherine Andrews’ post) as the inventor of the nickname “Butterstick” for the National Zoo’s baby panda:

Web logs, such as dcist.com, nicknamed the cub “Butterstick” because zookeepers described him at birth as being “about the size of a stick of butter.” According to Chinese tradition, the cub won’t be officially named until he’s 100 days old.

Butterstick, born through artificial insemination, now weighs more than four pounds. He no longer resembles a “terrible, furry spaceworm,” as one blogger wrote, but a chubby miniature panda with the trademark black and white markings.

They note this:

One local not caught up in the fuss is the father, Tian Tian. “They don’t play a role” in parenting, Long said. “He’s probably in his air-conditioned grotto, eating bamboo and fruitsicles and sleeping a lot. He’s doing the panda thing.”