夜郎自大的英文：
[Literal Meaning]
the state of Ye Lang/self-conceited
ludicrous conceit of the king of Yelang

[解释]
人无知而狂妄自大。

[Explanation]
parochial arrogance

[例子]
你还和他吹嘘你有钱，别夜郎自大了。他可是我们这里有名的百万富翁。

[Example]
You've boasted you are rich to him. You are stuck up and he is the well-know millionaire here.

[英文等价词]
to get too big for one's shoes
be stuck up

A cock is valiant on his own dunghill
夜郎自大

Every cock crows on its own dunghill
夜郎自大

Having limited outlook and being ignorantly boastful are common failings of the people in opposition to the reform.
坐井观天，夜郎自大，是反对改革的人的通病。

Keep it, in any case, familiar, facetious even, rather than pedantic and portentous
无论如何，要使它显得很随便，甚至滑稽可笑，而不要显得很迂腐，夜郎自大。

He was handsome and unattractive, a swashbuckling, beefy, conceited man who was putting on fat
他样子挺英俊，可就是不讨人喜欢;长得结实粗壮，身子已经开始发胖，这个人夜郎自大，欺软怕硬。