Old Phoebe

Haven't read the book, although when I went to school it seems that most US schools required it at some point, that's how popular Catcher In The Rye is. So I'm coming in cold.

Frequently "old (name) " or "good old (name)" is used to describe someone who is very familiar to the speaker. It can be applied to somebody younger or older, doesn't matter. It can be used as a positive or negative.

Here is a positive example: "I've known old Joe for years, he'll do the job right."

Here is a negative example: "Old Joe did it again-set the whole project back two weeks because he didn't pay attention to instructions".

It tends to be used in informal speech.

Here, "old" is used both as a term of familiarity and endearment.

Thank you so much for your explanation.
Very helpful. Plus, I got to know what it means to 'come on cold'.
Thank you again.

Familiarity and endearment.
Got it. Thank you, InfraBlue.

SMickey:
Thank you. Although I would just like to add that the expression I used was "come in cold", not "come on cold".

"Coming in cold" to a situation means that you don't have any background on it or time to familiarize yourself with it when you are forced to deal with it. I believe it is a baseball expression having to do with a substitute pitcher needing ten minutes or so to warm up his throwing arm before he can enter the game and play effectively.

"Coming on cold" is something else. To "come on (adjective)" means to show by word or deed a certain attitude. For instance, a person who walks up smiling to a stranger at a meeting, introduces himself, shakes his hand and starts pleasantly talking is "coming on friendly". On the other hand, a person who stands away from people, speaks in short, impolite sentences and moves brusquely away is "coming on cold". "Coming on strong" means that the person is trying to overwhelm you, verbally or otherwise. They are putting forth an attitude, good or bad. "Coming on (adjective)" is also an informal expression.

Come in cold is new to me, that's probably because it's a baseball expression, so I'm on a bit of a sticky wicket where baseball is concerned.

We wouldn't say coming on cold we'd say coming across (as) cold.

Oh, my mistake.

I figured you used the idiom 'come in cold' just because you said you hadn't read it and I asked something about the book.
I was able to understand when to use the expression - come in cold.

Thank you again for other expressions too.
Very helpful. Many thanks.