If someone has you over a barrel, they have put you in a situation where you are forced to do what they want. The unions wish they had more options. Jobs are tight, they know that, and they feel management has them over a barrel. And now this time they've got them over a barrel. Note: This expression may refer to a method used in the past to save someone who had almost drowned. The person was placed face down over a barrel, which was then rocked gently backwards and forwards until all the water had drained from their lungs.