Grant's mouth flapped for a moment like a fish out of water.

His mouth flapped; he couldn't speak, only made a small gasping sound like pain.

The toothy mouth over the doorway flapped its red lips as though whispering a promise.

His mouth, a soft round thing, was flapping and making noises.

She drank pop incessantly and that mouth of hers flapped all the time.

The one on the left showed the controversial talk show still in progress, the sound off, the mouths flapping without meaning.

His mouth flapped, but no sound came out.

He knocked the chair back, and his mouth flapped with a frozen scream.

The woman's mouth had flapped idly during this speech.

My mouth was flapping but absolutely nothing was coming out.