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Extremely naïve, gullible, or unintelligent, like a newborn baby. Almost always used in the negative or as a rhetorical question. Don't think you can fool me with that old ruse, I wasn't born yesterday, you know. Of course I know that major political issues can't be fixed overnight. Do you think I was born yesterday?
Someone who has passed the pinnacle of his or her career. Bob is never going to give up his cushy job—he's yesterday's man, and his next career move is retirement!
be born yesterday
To be naïve or easily deceived. Often used in the phrase "I wasn't born yesterday." Oh, you expect me to believe that you've been in your room all night and didn't just sneak in the house a few minutes ago? Well, I wasn't born yesterday—and I heard the door open! Do you think I was born yesterday? There's no way that email isn't a scam!
I need it yesterday.
Inf. an answer to the question "When do you need this?" (Indicates that the need is urgent.) Bob: When do you need that urgent survey? Bill: I need it yesterday. Mary: Where's the Wilson contract? Sue: Do you need it now? Mary: I need it yesterday! Where is it?
need something yesterday
Inf. to require something in a very big hurry. Yes, I'm in a hurry! I need it yesterday! When do I need it? Now! Now! No, I need it yesterday!
not born yesterday
Fig. experienced; knowledgeable in the ways of the world. I know what's going on. I wasn't born yesterday. Sally knows the score. She wasn't born yesterday.
Yesterday wouldn't be too soon.
Immediately.; Right away. (An answer to the question "When do you want this?") Mary: Mr. Franklin, when do you want this? Fred: Well, yesterday wouldn't be too soon. Alice: When am I supposed to have this finished? Sue: Yesterday wouldn't be too soon.
I/he/she wasn't born yesterday!
something that you say in order to tell someone that a person is not stupid and cannot be easily deceived You'd better think of a better excuse about the dent in my car. I wasn't born yesterday, you know! You can't expect your mother to believe that - she wasn't born yesterday!See There's one born every minute
See also: born
not born yesterday
More experienced and less naive than one appears to be, as in Don't think you can fool me; I wasn't born yesterday. This term gained currency from the title of Garson Kanin's popular Broadway play, Born Yesterday, which was made into an even more popular film. In both, Judy Holliday played a stereotypical dumb blonde who shows more common sense than her sophisticated acquaintances. [Early 1800s]
Naive or ignorant. Used in negative constructions: Of course I can use a computer; I wasn't born yesterday.