"I cannot get my foot to stop taking a rest." When his foot had fallen asleep.
"My eyes won't let me keep them open." When riding in the truck. I told him it was okay to close them and within seconds he was asleep.
"Because I am four and a half!" When asked "How did you get so strong/fast/smart/whatever?"
"I have really bad news!" When he had gotten a papercut and was going to let us know.
"You are the best mom in the whole world."