What is your problem?

Rob, Christopher, and I were sitting at the table eating dinner, and Christopher and Rob were being goofy, when all of a sudden Christopher blurts out, "What is your problem?" all at once.  Clear as a bell.  Both Rob and I heard it at the same time and were like -- "That sounded exactly like 'What is your problem!'"  It was hilarious.  Another new thing Christopher is doing: Whenever he's doing something naughty he covers his eyes --like I won't be able to see him anymore!  It's too cute.  He's my little stinker butt.