Adjective phrase meaning that your assumed position is slightly larger than the actual position you belong in, hence the idiom referring to the too big for the pair of pants.
When you smarted off to the boss yesterday, everyone in the office thought you were too big for your britches.
by rhetorensic December 18, 2009
After Richard Nixon became too big for his britches people became even more difficult for politicians to understand. (example of too big for one's britches)
by The Return of Light Joker December 06, 2009