Sweet Potatoes and Elephants?!

What do sweet potatoes have to do with elephants?
A lot, I guess, in a 22 month old mind. I cut the swisted end off of a sweet potato and gave it to Tyler to entertain him for awhile while I peeled. He was really studying it, and then he began to raise his arm and make a trumpeting sound (the sign we've been using for elephant)! So I was the one who was really entertained!