Used to describe (generally female) imagery that's suggestive, but in a PG-13 sense rather than an R or above sense.

The act of a female "going commando." It can get pretty messy down there, so it is up to the labium majora and labium minora to flap around freely and fight off any kind of dirt or grime.

The act of not wearing underwear, for females. Just as mud flaps behind the wheels of a truck flail wildly in the wind, a saggy vagina may mimic this flapping motion without the restriction of underwear. This is the alternative to "free balling" meant for female use only.