Flap-Fest Share definition Flag The complete opposite of a sausage party. When you have a party or gathering and only girls show up. Sarah: Damn, No guys showed up at all.Kim: Yeah, it's a total flap-Fest. Flap-Fest by RainbowJohnson October 20, 2016 0 0 Get merch Get the Flap-Fest mug. Buy Now — $32.95 See more merch