Your dad thought your mom was lying. Or at least exaggerating. "Estelle now plays Peek-a-Boo," she said. Your aunt Jess nodded enthusiastically. "Look at you," your aunt Jess said as you gripped her fingers. Your dad tilted his head to the side, like a curious and confused dog, but said nothing, also like a curious and confused dog. Your dad had not witnessed any previous behavior resembling the act of Peek-a-Boo.
Later that evening, as your mom stepped out of the shower after a Jillian Michaels workout, your dad tossed a rag over your face. You immediately reached up with both hands and pulled the rag down. "Peek-a-boo?" your dad asked. You pulled the rag back up over your face, then pulled it back down, then up, then down. "Hey," your dad admonished. "You have to wait." You pulled the rag up again, then down. "There hasn't been enough time to build suspense," your dad explained." Up, down. "Peek-a-boo only works if I theoretically lose sight of you and have to ask, theoretically, 'Where'd baby go?' "
Your mom laughed. The rag stayed down and you gave your dad a newly-minted Big Cheesy Grin. Eyes squinted, nose wrinkled, lips smiling to fully expose your lower gums. "Um, that's new too, isn't it?" your dad asked. "Isn't it hilarious?" your mom said. "I think it might be the very first expression that's completely hers."
You always had your mom's megawatt smile. But that smile had always been separate from your eyes. Then your eyes gradually added to your smile, but only as a hint. Now, this freshly-patented Big Cheesy Grin comes into play, which would appear mischievous if you had any ulterior motives whatsoever. As it stands, your dad has no reason to think you're lying, or even exaggerating.