Shaky 是指动摇不稳定, 不太确定,  通常就是指一个人不太可靠. 另外 Shaky 也可以用来形容数据, 像是有一次教授就在课常上说, The data is shaky, 就是说这些 data 怪怪的, 不太可靠.  Shaky 另外有一个惯用法, He has a shaky start. 就是说有人要上台报告准备却不够充份, 以致一上去就开始紧张, 冒冷汗, 不知所云, 这种情况老美就会说, He has a shaky start. 或是另一个很意思很接近的说法, "He has a bumpy¹ ride." 

10. Don't act black.
不要跟黑人一样.

虽然现在都已经快要迈入二十一世纪了, 不过时至今日还是有些白人会歧视黑人的, 尤其是老一辈的白人, 有时候他们的孩子作错了什么事, 他们还会骂说 Don't act black. 但是这是句非常有种族歧视的话, 不要乱用,   当然也希望各位国人来到国外时要为华人争一点面子, 不要让老美说 Don't act Chinese. 那样就很不好了. 

附记:  曾有人写了一封信跟我谈到, 关于 'suck' 这个字该不该用. 大家参考看看.

I noticed something that I wanna tell you.. Maybe it's not a big deal actually.  In your message, I saw a word "sucks" um.. I think that's not a good word though... you know I think girls souldn't say that words.. even a guy... I don't know I can hear that word all over the place but I still can't get used to it.. in my opinion, that's worser than say "fuck" or "shit" but that are all bad words anyway.. ok, don't say those words ok? cause I have very expectation on you and I don't want to hear those words from you ok? maybe it's not that big deal though.... don't know.. 笔者是觉得在美国说 suck 或许没有 shit 或 fuck 来的这么槽, 但是没把握还是不要乱用这个字比较好. 如果要用, 请用在同辈之间及比较熟的好朋友身上.