lick the stuffing out of (one)
1. To strike or assault one violently and severely. "Lick" in this sense means to beat thoroughly. Likened to the cotton stuffing of a stuffed animal being knocked out of it by severe blows. Hey, watch it, pal, or I'll lick the stuffing out of you! Two guys mugged me and then licked the stuffing out of me last night.
2. To damage or lower one's confidence, motivation, or self-esteem. Boy, that performance review really licked the stuffing out of me—I just feel like I can't do anything right anymore.