1. the bees knees <俚>最最了不起的人或事物；顶尖儿
If you are in formal situation and want to say that something was fabulous or brilliant you can use this phrase.
e.g. —What did you think of that show？
—I thought it was the bees knees！
2. chuffed to bits <俚>心满意足
You would be chuffed to bits if you were really pleased about something.
e.g. —My parcel finally arrived today.
—I bet you are chuffed to bits！
3. I wasnt born yesterday. 我又不是三岁小孩。
Used if you believe a person is trying to trick you or tell you something that isnt totally true.
e.g. —This is definitely the most popular restaurant in town.
—I wasnt born yesterday； its nearly always empty.
4. cheese off <俚>对某人或某事非常不满；使感到厌倦；使沮丧失望
A polite way of saying you are very annoyed with something or somebody.
e.g. I am so cheesed off with John not inviting me to the party.
5. come on 得了吧
Used when a person thinks he or she is being lied to， or feels as if he/she is being messed around.
e.g. —My dog ate my homework， teacher.
—Come on， do you think Im that stupid？