Little kids are the best liars. More accurately, little kids are the most committed liars. No matter how badly the evidence is stacked against them, children will stick to their stories no matter what.
Here, Jack confidently tells his father that he didn't eat a cupcake, even though he's clearly been caught red-handed, or should we say "blue-mouthed." He even goes as far as providing an alibi for himself that falls apart immediately, considering Jack is a toddler who can’t go anywhere without his parents. We may never know what happened to that cupcake, but we do know that we should never leave our cupcakes unattended when Jack is around.