hypocritical [chaneph] mockers [la`eg] in feasts [ma`owg], they gnashed [charaq] upon
me with their teeth [shen]. KJV-Interlinear
profane mockers at a feast, they gnash at me with their teeth. ESV
Profane mockers, refers to those who have no respect for God, for Christ, for truth, ad so they mock everything that is real, and boast about all that is not real.
In feasts, designates those types of people who make a scene at parties, drunks, slurring, loud, obnoxious, people who stammer or speak a foreign language. They boast of themselves or of their things. Boasting always leads to the loss of that which you are boasting.
This is not a reference to foreign people, but describes the behavior of those who, when they reject truth and reason, take on the actions of obnoxious people.
Drunks, describes the confusion of the mind. Foreign, describes that they are not a functional part of Gods family, by either being unbelievers or out of fellowship believers.
Gnashing of the teeth, describes the hateful and rowdy and mouthy attitude.
But this is not just the overt activity of people who mocked Jesus, it describes all people who reject or disregard doctrine.
They are nothing more than dysfunctional and profane mockers, fools that favor lies instead of truth.