[flashback to Lily and Marshall talking to Robin at MacLaren's:]
Lily: He said that? Oh, my God! What a tremendous ground-breaking surprise!
Robin: How long have you known?
Lily: 8 months.
Robin: And you've kept it a secret since then? Good for you.
Marshall: Yeah, wow. Good for you, Lily. I mean, what a bombshell. Who saw that coming?
Robin: How long have you known?
Marshall: Seven months, 29 days.