Marshall: Baby, I know, I know. But, listen, there will be plenty of other Marvin firsts. His first day at school, his first trip to meet Santa, his first touchdown pass for the 2032 Super Bowl champion Vikings - no pressure. I'll love him even if he runs the ball into the end zone. So can we please just let this crawling thing go?
Lily: Yeah, okay. You're right. I mean, I'm being nuts. We'll see it when we see it.
Marshall: Yeah.
[later, Lily aims a video camera at Marvin:]
Lily: Do it. If you ever want to see these boobs again, crawl, you son of a me.
Marshall: Come on, Lil. You know what they say: a watched tot never crawls. Or calls you later in life, after it sees this disturbing footage.