Someone who thinks they can rap but they can not. So they just flap their lips trying to rap about absolutely nothing.

The act of a fat male or female dancing or jiggling prefeucely without reason

The highly velocitized escape of gaseous matter via the rectum whereby the rim of the sphincter is first inadvertently puckered inward, then violently blown outward causing a momentary flapping as the blast escapes then subsides. The turbulent build up generally occurs as the sphincter is squeezed shut for extended periods. First dates, group meditations, and solemn religious ceremonies frequent such occurrences.

The release of loud flatulence that sounds noticibly moist and wet. The hallmark of the Moist Flapper is that the flatula released always sounds wet but may not always actually be wet and result in the release of any feces aka Moose Jelly requiring a quick wipe.

When the external labia are so large and pendulous, that they flow freely in the breeze, loudly slapping against the inner thighs and each other.

The act of flapping porn cards on the Las Vegas Strip. The flapping sound is the cards hitting the below minimum wage workers hand a split second before he/she extends the hand for you to take or not take said card.

When a woman's vaginal lips are so loose, that when wet, flap together as she walks, making the sound of bologna flapping in the wind.