fluff up
phr. v..phr. v.. to shake or pat something soft, like a pillow or your hair, so it looks full and light again.
phr. v.. to make something soft or fibrous more voluminous by shaking, patting, or loosening the material.
She fluffs up the pillows every morning.
The bird fluffed up its feathers to stay warm in the cold wind.
Before the guests arrived, the decorator took a moment to fluff up the cushions and straighten the silk throws.
usually used with soft objects like pillows, cushions, hair, or feathers.
this is a great example of a phrasal verb where the particle 'up' indicates an increase in volume or size; contrast with 'flatten' or 'squash'.
He fluffed up it before sleeping.He fluffed it up before sleeping.when using a pronoun like 'it', it must go between the verb and the particle in this optional separable phrasal verb.