Beat the tar out of one American informal verb phrase
The verbs "knock" and "whale" can be substituted for the verb "beat".
Beat or attack someone repeatedly and forcefully
They saw him beating the tar out of his dog with a stick.
It's cruel to beat the tar out of children.
Beat someone decisively in a competition
Bob always beats the tar out of me in tennis.
The verb "beat" should be conjugated according to its tense.
The expression may have been brought to this country by some Scottish or north-of-England sheepherder who may have used it in a literal sense. Many centuries ago it was learned that a sore on a sheep, as from an accidental cut in shearing, could be protected against the festering bites of flies if smeared with tar. However, when tar once gets embedded into a sheep's wool, its removal is difficult. Thus, used in a literal sense, to beat a sheep's side for the removal of tar.