This struck me as a milestone today.
So Mudpup (Alleluia Boy, whatever) is standing in front of everyone seated in the living room. With a big smile, he sings, "Rain, rain, go away, [Mudpup], go away!" People smiled back, and he continued "Rain rain, go away, Ju Ju, go away!" Everyone really cracked up then (although Jaybird had mixed feelings about it). So he continued, "Rain rain, go away, Ben Ben, go away!"
Yes, it's two year old humor.
He's also repeating (the memorized) Brown Bear, Brown Bear, What Do You See? book, verbatim, about 90% of the way through. He's enjoying that, do the reading "himself".