When a girl puts her clit on a guys nose after sitting on his face and jiggles her pussy lips around...therefore making a flubber sound from the mans mouth.
Caution: must not be tried on just anybody...must be experienced and prepared, for flubber lipping may cause pussy juices to run into ones nostrils and nasal cavaties causing cum leakage from the nose for a few days.

Literally everyone, ever. Including the writer of this definition.