内緒にしておいてねって英語でなんて言うの？

Off the record' means the information is not to be shared.
It can be used between strangers or acquaintances.
The second two sentences are used more between friends.

You can use these when you want to tell your friend to keep a secret.

On the QT means on the quiet - or secretly
for example - She went round to see her friend on the QT - it was a secret and she didn't tell anyone.
There are other ways of saying secret;

Keep schtum - this means keep it quiet - do not talk about it. It can also be spelt - shtum

Hope this helps
Jane:)

Your can use any of the above to tell someone to keep something a secret.

I'm keeping it on the DL
Meaning = I'm keeping this quiet

DL = down low
Meaning = I'm not telling anyone. I'm keeping it a secret

Don't tell anyone, its a secret
Meaning = this is what you would say to someone if you told them something you want to keep secret.

I'm keeping this hush hush
Meaning = I'm not telling anyone

Hush hush
Meaning= quiet / not telling people / keeping it quiet / keeping it a secret

You can also say:

Please don't tell anyone I want to keep it quiet
Meaning = I don't want you to tell anyone

This is strictly between me and you
Meaning = this information is only for me and you to know. Don't tell anyone

This shows that it is important to you if they keep it to themselves.

1. This uses the imperative form to instruct the listener not to pass this secret on to anyone.
2. This emphasises that the secret must not be repeated to anyone.
3. This is a hyperbolic threat used in a conditional sentence. The listener has an option to tell someone the secret or not. If the speaker's trust is broken, the speaker will not, of course, kill anyone. It is exaggerated speech to stress a point.

In the first sentence, you have used the phrase 'top secret' which, in this context, means 'extremely secret information and not to be told to anyone outside a particular group of people'.

In the second sentence, you have used the adverb 'strictly' which means 'completely or entirely'. Then, you have added the 'adjective 'confidential' which in this context means 'secret, often in a formal, business, or military situation'. So, you may say: This is strictly confidential.

In the third sentence, you have used the verb 'revealed' in its past tense. The verb to 'reveal' in this context means 'make (previously unknown or secret information) known to others'. So, you may say: This is not to be revealed to anyone else.

If you want someone to keep a secret, then you can use any of these statements:-

1. Please do not tell anyone else.
   If you tell someone some information and you tell them not to tell anyone else, then that information is a secret just to be kept between the both of you.

2. This information is top secret.
   Information that is top secret means that it should not be shared with anyone else.