"Get back on his rocker" what does it mean?

Question

I have met this phrase watching The Big Bang Theory TV-series. The full scene is: Sheldon took offence at Leonard and got freaked out (as it was called in the movie) because he has called Sheldon's mother. All characters except Sheldon prepared to eat, and mother is praying before start to lunch:

Oh, Lord, we thank you for this meal and for all your bounty. And we pray that you help Sheldon get back on his rocker.

No one literal meaning of rocker I have found doesn't seem to fit the situation. Though I have found an idiom off your rocker. So is get back on his rocker means here something like that he needs to get back to a normal state?

Answer 1

Back on one's rocker can probably be considered idiomatic, but it is nowhere near as common as off one's rocker. This is a kind of joke where you "de-idiomize" a phrase to create a (possibly strange sounding) reference to the idiom without stating the idiom itself. I'm not sure if this has a technical name; it might be considered a play on words.

Here's another example using the idiomatic expression to ring up (meaning check out at a cash register):

"Sorry, I already rang it up."

"Well ring it back down!"

Of course, to ring down is not an idiomatic expression.

Even if the proper idiom isn't stated, someone who is very familiar with the expression will recognize the derivative phrase as being a reference to the idiomatic expression (context is important too).

In summary, the answer is yes, back on one's rocker means no longer off one's rocker, i.e. the person has gone back to being sane.