In the St Mungo's Waiting Room 1981:
Remus (looks at the clock): Oh wow, 3 hours and still no baby from Lily and James. Ugh, the miracle of birth sure is a snooze fest
Marlene: Hey, you wanna see something?
Marlene: This is going to be fun. Watch me freak out Sirius. Honey?
Marlene: Listen, I’ve been doing some thinking, and I don’t know whether it’s because we’re here at St. Mungo or Lily’s giving birth but…I think we should try to have a baby
Marlene (freaks out): Wh-what’s that now?
Sirius: Okay. I’ve been thinking about it too, and I think we’re ready.
Marlene: What? Are you kidding me? Y-you think we’re ready to have a baby now?
Remus (grinning): Oh, this is fun
Peter, to Sirius: You’re ready to have a baby? My boy’s all grown up!
Sirius: But you said you were ready too
Marlene: Yeah but I was just screwing with you to try to get your voice all high and weird…like mine is now!
Sirius: Yes, but haven’t you wanted a kid like forever?
Marlene: Okay, just back off mister! Whoa. Because I am ready to have a baby. I just want er…Peter to be the father
Peter (voice all high and weird): What? Are you crazy?
Marlene: That’s it! Right there! Is all I wanted!