You said it! (AmE, BrE)

[retro]

I heard that "you said it" differs in meaning in BrE and AmE.
Allegedly, it is used in BrE to agree with somebody when they say something that would also apply to you.
- I know I'm not a good cook.
- You said it!

On the contrary, in AmE it is used to agree with sb's suggestion.
- How about eating out tonight?
- You said it!

My other question is: can we also use "you can say that again" in both examples (in the first one when you intend to be rude)?

Any suggestions?

[MikeNewYork]

I heard that "you said it" differs in meaning in BrE and AmE.
Allegedly, it is used in BrE to agree with somebody when they say something that would also apply to you.
- I know I'm not a good cook.
- You said it!

On the contrary, in AmE it is used to agree with sb's suggestion.
- How about eating out tonight?
- You said it!

My other question is: can we also use "you can say that again" in both examples (in the first one when you intend to be rude)?

Any suggestions?

I can only speak for AmE.

"You can say that again" is used when one agrees with another's opinion or position. It really wouldn't apply to a suggestion about dining out.

[retro]

I can only speak for AmE.

"You can say that again" is used when one agrees with another's opinion or position. It really wouldn't apply to a suggestion about dining out.

And what about "you said it"? Can it be used in the "eating out" example?

[Philly]

And what about "you said it"? Can it be used in the "eating out" example?

I wouldn't use it that way.
.
I'd use "You said it" to agree with an opinion, for example (similar to "You can say that again.").
.

[Tdol]

As a BrE speaker, I would only use 'You can say that again' with the first example.