It's contagious. I wish I had caught it on camera because this moment was priceless. I was singing to McKenzie about her feet, something along the lines of, "I tickle your toe, a do-ba-do-ba do..." and Dustin's brother, who was doing dishes in the same room, chimed in "do-ba-do-ba-do-ba-do-ba-dooooo." I started laughing, he had no idea why. I proceded to tell him that he has a nice singing voice and he looked at me dumbfounded. Apparently he had no idea he was singing along.
He is moving out this weekend into an apartment with a stranger...hope he doesn't sing to her about tickling her toes.