I can't recall how the exact quote goes, but it's from the episode where Penny throws the Halloween party and the guys are being insulted by her ex-boyfriend (who is HUGE, and muscled, and dressed like a caveman).
"A homunculus who is just discovering his opposable thumbs says what?"
"...What?"
*Proud giggles*
Also, "Awwww, you're my little homunculus!" My husband says that to me all the time, since I am also a small, perfectly-formed human.