too big for one's britches



too big for one's britches ‎(not comparable)

  1. (idiomatic) Disturbingly confident, unacceptably cocky.
    • 1989, Edwin M. Reingold, "Hard Times for Teflon Tom," Time, 22 May:
      A diffident, dedicated man, Bradley seemed the personification of rectitude. He never got too big for his britches.
  2. Used other than as an idiom: Too large to fit into one's pants.