She's a natural crier.
她是个天生爱哭的人。

natural 天生的；本能的；与生俱来的

eg. Remember that these weaknesses are natural.
记住这些弱点是天生的。

He's really a law-down dirty shame.
他真是个不知羞耻的家伙。

law-down dirty shame“不知羞耻的”

eg. I wouldn't like to have anything to do with a law-down dirty shame like her.
我可不想和她那样不知羞耻的人有任何来往。

He's good-time charlie, feeling no worries and anxieties.
他可是个乐天派，整天无忧无虑的。

good-time charlie 汉语中“乐天派”可以用optimistic来表示，也可以用good-humored。但是上述表达法缺乏口语色彩，而用good-time Charlie比较合适。

She's said to be a jinx.
有人说她是扫帚星。

jinx 通常指不吉利的人或物。其实“扫帚星”指的是“彗星”。在英语中没有对应的比喻义的翻译，不能译为“comet”，应该是jinx。

eg. I've heard of her. She's said to be a jinx, who would bring bad luck to whoever she marries.
我听说过她，有人说她是个扫帚星，谁跟她结婚都会倒霉。

Lucas has a lot on the ball.
Lucas很能干。

on the ball 有能力的或有效率的：

a manager who has a lot on the ball;a student who has nothing on the ball.
一个很能干的经理；一名什么也不会的学生。

He's really a party animal.
他真的是个聚会狂。

party animal指的是特别喜欢参加聚会的人，也就是聚会狂，他们哪怕一次聚会也不会落下。要注意，这里animal说的可是人哦，并不是把人贬低成了动物。

eg. I'd love to invite that party animal to the party. He'd liven up the mood!
我很喜欢邀请那个派对狂来参加我们的派对。他能使整个气氛热烈起来。

You're still wet behind the ears.
你还嫩点儿。

Wet behind the ears如果直译: 耳朵背后是潮的。它可能来自这样的说法: 小马、小牛刚生下来的时候全身湿漉漉的；别的地方很快会干，但是耳朵背后却还是湿的。所以说某人耳朵背后是潮的，是把这人比作刚生下不久的婴儿了。换句话说就是他简直像新生儿一般幼稚无知。

eg. He was too wet behind the ears to bear such responsibilities.
他太年轻了，不能担此重任。

That boy never says uncle.
那个孩子的嘴特别硬。

never says uncle 嘴硬，不服输

eg. He never says uncle. He's never heard to admit that he's wrong.
他可是个嘴硬的孩子,从没听他认过错。

He always likes to play a lone hand.
他喜欢单枪匹马地去干。

play a lone hand〔美国〕独个儿工作[旅行、生活]，不靠别人

eg. He's not the sort to enter into partnership.He prefers to play a lone hand.
他是不喜欢和别人合伙的，他宁愿单干。

Tom is the black sheep of his family.
Tom是个败家子。

a black sheep“败家子”此短语源于谚语 There is a black sheep in every flock.（每群羊里都有一只黑绵羊）

eg. Dick is a black sheep, always bringing trouble to his family.
Dick是个败家子，总给家里招惹麻烦。