Question: When Meg came back home to announce that she's a flag girl Stewie replies by saying "now you can be somewhere else when the boys don't call." I don't get it - can someone please explain it to me?
Answer: There is an old stereotype that people on the flag team, or (at some schools) the "color guard", were not good enough for the cheerleading team. "Losers", "dorks", etc. Meg thinks that joining the flag team has finally made her popular, but Brian and Stewie are aware of the stereotype. Stewie is saying that nothing much has changed; she simply has a new activity, where she will be the same "loser" type.
Answer: It's long been a running joke that Meg is unpopular; Stewie meant that now Meg will be busy with her flag girl duties rather than at home where presumably no boys will be calling for her.
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