beat the stuffing out of (someone)

beat the stuffing out of (someone)

To strike or assault someone violently and severely. Likened to the cotton stuffing of a stuffed animal being knocked out of it by severe blows. Hey, watch it, pal, or I'll beat the stuffing out of you! Two guys mugged me and then beat the stuffing out of me last night.
See also: beat, of, out, stuffing