to suck on or suck in something with the mouth; to absorb

to suck; to draw into the mouth by contracting the muscles of the lips and mouth

To perform the most degrading acts of servile flattery or sycophancy to gain favor from powerful people; based on an ancient story about doctors being rewarded with chariots for cleaning a king's abscesses or hemorrhoids with their mouths.

to lick with the tongue and suck in; to lick clean