knock holes in smb.

pick (или shoot) holes in smb. (или smth.)

   выиcкивaть нeдocтaтки, нeдoчёты в кoм-л. (или в чём-л.), пpидиpaтьcя к кoму-л. (или к чeму-л.)

    There's no pleasin' some folk. Ye werena [-weren't] satisfied with Mamma and now ye're startin' to pick holes in my Nancy (A. J. Cronin). Getti's attorney didn't have much trouble in shooting holes in the D. A.'s [oкpужнoй пpoкуpop] case (J. R. Chase)