great phrases in the english language

Could it be that it's an American cereal that's marketed as being British in the US?

a sort of liptons scenario? could be. odd reversal of history of breakfast cereals if so. and how the fuck did it enter the language? american films?

OED

c. Sunny Jim, the name of an energetic character employed as the proprietary name for a brand of breakfast cereal; also used allusively, as a term of address, and as a nickname. Also Sonny Jim (influenced by sonny n.).
‘Sunny Jim was the creation of an American schoolgirl called Ficken (not Fincken) and the various jingles which accompanied him were written by Miss Minnie Hanff. It is believed that Sunny Jim was the winning entry in a competition run by the Force Food Company to find a suitable advertising character to promote “Force”.’—C. Fincken (A. C. Fincken & Co. Ltd., manufacturers of Force), private let. to ed., 24 June 1983.

1903 Poster High o'er the fence leaps Sunny Jim ‘Force’ is the food that raises him.
1904 Trade Marks Jrnl. 30 Mar. 381 ‘Sunny Jim’... Cereal Food Products. The firm trading as the ‘Force’ Food Company, 6, Holborn Viaduct, London, E.C.; Manufacturers.
c1904 Story of Sunny Jim (Force Food Co.) Jim Dumps was a most unfriendly man, Who lived his life on a hermit plan. He'd never stop for a friendly smile, But trudged along in his moody style. Till ‘Force’ one day was served to him. Since then they call him Sunny Jim.
1911 G. K. Chesterton Innocence of Father Brown xii. 315 Sir Aaron Armstrong was..comic... It was like hearing that Sunny Jim had hanged himself.
1911 ‘I. Hay’ Safety Match xii. 187 Mr. Blunt..cleared the topmost rail... ‘Now then, Sunny Jim!’ remarked a reproving voice.
1916 Punch 5 Apr. 229/1 [He] says he's quite a Sunny Jim, That buoyant health and youthful vim Are sticking out all over him.
1943 Current Biogr. (1944) 779/2 Vandegrift—so cheerful that he has earned the nickname ‘Sunny Jim’—is..the toughest Marine Corps leader who ever charged at the head of his troops.
1960 D. Storey This Sporting Life i. v. 127 ‘All right, all right! Don't preach, sonny. Hey!’ she calls to the M.P. ‘Hey sonnyjim! What kinda car has Arthur Machin got?’
1962 S. L. Goldberg Joyce i. 3 What his [sc. James Joyce's] early works do not portray..is the aspect of his character that earned him the family nickname, ‘Sunny Jim’.
1967 A. Wilson No Laughing Matter ii. 127 Does your Mother know you're out, Sonny Jim?
1976 Times 6 Apr. 16/1 The new Prime Minister [sc. James Callaghan]..enjoys life... He is not called Sunny Jim for nothing.

1911 being the first 'reproving' tone there, presumably from waywardness as a result of excessive energy. GKC a pioneer I see.

https://en.wikipedia.org/wiki/Force_(cereal)

In 1903 a British subsidiary of the Force Food Company was formed to import the cereal to Europe. A slightly modified version of Sunny Jim and his jingles caught the fancy of British consumers. A. C. Fincken, a former employee of the Force Food Company, set up an agency in 1910 to import American cereals to the UK. The cereal, and the Sunny Jim character, achieved wide success in Britain, at its peak in 1930 selling 12.5 million packages.

Manufacture of Force cereal ceased in 2013,[4] the reason cited being poor sales, although in the last few years of production the cereal had been difficult to find due to having very few suppliers, latterly only Sainsbury's, Waitrose and Ocado.

Since then, the Force wheatflakes brand was revived for UK consumers, and was acquired by Nestlé. It was, but is no longer, for sale on the Waitrose website. [5]

2013!

Google Ngram Viewer: '[Sonny Jim]', '[sonny Jim]', '[Sunny Jim]', '[SUNNY JIM]', 1800-2000 in English.