Wood shed is an outbuilding where the firewood was kept back in the olden days. Usually there was room inside for a couple of seats (unsplit logs) to facilitate smokin' & jokin'. However, it was also a convenient and enclosed space to deliver an ass-whuppin' in relative private without disturbing the better-behaved children of the house. These days a "woodshed moment" is not limited to a beating, and can apply to disciplinary conferences in an employer/employee relationship.
"What the...Brad botched the meeting and cost us a client! When he gets in we're going to have a woodshed moment."
by ChickenThe Cat October 10, 2018