Wiktionary
a. (context idiomatic English) In a disadvantageous or helpless situation, especially one in which one may be controlled or victimized.
Usage examples of "over a barrel".
He kept leaning down on the doctor, making him squirm with that grin and waiting for him to admit he was over a barrel.
They've got you over a barrel, because of your connection to some supposed ‘.
Zane believed he had Satan over a barrel, for the review would surely expose evidence of Satan's cheating and free Luna from the sentence.
In layman's terms, with two Legionnaires under lock and key, he had their commander over a barrel and had no intention of settling cheaply .
Zane believed he had Satan over a barrel, for the review would surely expose evidence of Satan’.
Their recreations were almost as coarse and violent: the dances, the athletic contests, the endless lovemaking, the bawdy songs roared out from full lungs over a barrel of sea-grain beer.