knock the starch out of (one)

1. To strike or assault one violently and severely. Likened to a stiff, starched shirt being beaten until it is limp. Hey, watch it, pal, or I'll knock the starch out of you! Two guys mugged me and then knocked the starch out of me last night.

2. To completely outclass, outdo, or outperform someone or something; to soundly defeat or best someone or something. Catherine knocked the starch out of the other kids in the spelling bee.

3. To reduce or damage someone's ego or pride; to humble or humiliate someone. His defeat in court really knocked the starch out of Tom. Don't let a silly performance review knock the starch out of you like that—you've got to have confidence in your own abilities.