That's cute and all, but what makes it really cute is that she does it on command. I had a good giggle at this one -- I hope you all do, too!
Her mom actually taught her this trick by tickling her lip with her finger until she lifted it... then she 'd get a cookie. Eventually she's do it if her mom just touched her nose. And then, after a while, she just started smiling all the time... just to get a cookie! Silly Lucy. Smart girl!