too big for one's britches(redirected from too big for one's boots)
too big for (one's) britches
Overconfident in one's importance, skill, or authority; behaving as if one is more important or influential than one actually is. He's gotten too big for his britches ever since he got that promotion. John's been too big for his britches now that he's been scouted by pro teams.
too big for one's britches
Also, too big for one's boots. Conceited, self-important, as in Ever since he won that tournament he's gotten too big for his britches, or There's no talking to Jill anymore-she's just too big for her boots. This metaphoric idiom alludes to becoming so "swollen" with conceit that one's pants or boots no longer fit. [Late 1800s]