It's grade "A"!/ this is "A"!

[GeneD]

When something we hear sounds particularly convincing or funny, we in Russian might say Это "5"/This is "5" ("5" is the best grade in Russian schools). Do you say anything similar in English? For example:

It's grade "A"!
This is "A"!

 

[Do228]

"It's an A-plus!" might be possible in some situations.
(Not a teacher)

 

[Yankee]

You might hear, for example, "I'd give that a ten!" (as on a scale of one to ten). And I would give your post a TEN.

 

[Tarheel]

"A-number one" is also heard.

Or number one.