There was a goblin arc not long ago. Phoebe was given goblin form by the unicorn. Why? Snooping. They wanted to find out why Dakota and the goblin queen were no longer friends. That’s when Phoebe discovered that goblins had perfectly intelligible speech… if you were another goblin. That’s also when Phoebe discovered that goblins eat wool scarves….
A friend with three daughters tells me that body function humor becomes big with girls about Phoebe’s age. (Cf. Vanellope in Wreck-It Ralph.)