Lucky Strike

Through most of the series, there was a running dark comic joke where Quinn pretended while at school or in public that Daria was not her sister. While Quinn would come sometimes come up with ridiculous fake identities for Daria, most of the references to this were made by Quinn's Fashion Club frenemy Sandy, who referred to Daria on several occasions as Quinn's "cousin or whatever", "that girl that lives with you or whatever" or "that exchange student that stays with you or whatever" (the last two when talking to Quinn). In Season 5, when Sandy tries to intimidate Quinn by implying Daria is her sister, Quinn overtly tells the class that Daria IS her sister; when Sandy pretends to act astonished about this, she ends up being humiliated as the other Fashion Club members (Tiffany and Stacy, both of whom are nicer than Sandy) bluntly say that they always knew Daria was Quinn's sister but didn't say so because they "were just being polite about it" to Quinn.

References The Wizard of Oz (1939)