大言不惭 blow your own trumpet：You really blow your own trumpet. (talk big; overshoot oneself)
大快朵颐 They are so delicious that I ate my fill. (gorge oneself; tuck in at; have/take one's fill.)
大功告成 The big project finally came off with honors (bring home the bacon; come through with flying colors).
大智若愚 He who cannot play the fool is not a wise man.
大器晚成 Rome was not built in a day.
大海捞针 needle in a haystack：Finding your lost contact lens is just like looking for a needle in a haystack.
山穷水尽 at the end of one's resources
山中无老虎，猴子称大王 Among the blind the one-eyed is king./When the cat's away, the mice will pay.
小题大做 Make a mountain out of a molehill. ( fuss about trifles; a tempest in a teapot; a storm in a teacup; break a butterfly on a wheel )
小Car笔记：
much of a muchness：大同小异very much the same
tuck：<俚>大吃，通常后面接away/in <tucked away a big lunch>
come off：实现，发生
bring home the bacon：成功，也有养家糊口，谋生的意思
play the fool：干蠢事，演滑稽角色
contact lens：隐形眼镜