Green’s Dictionary of Slang

cheerful, merry, esp. after drinking.

1770		Gent.’s Mag. Dec. 559/2: To express the condition of an Honest Fellow [...] under the Effects of good Fellowship, it is said that he is [...] 32. Cherry-merry.
1793		Bacchanalian Mag. 22: While thus cherrymerry, / Let Harris and Derry / With faces uncommon supply us.
1833		‘Ye Rakehells So Jolly’ in Swell!!! or, Slap-Up Chaunter 26: While thus cherry merry, let Harris and Derry / With faces uncommon supply us.
1838		Sydney Monitor 20 Apr. 4/4: [A] fortnight after plaintiff arrived in Demerara witness saw him on one of the public wharfs very ‘cherry-merry’ (loud laughter - that was, pretty drunk).
1840		‘The Tippling Deities’ in Capt. Morris’s Songs in Spedding & Watt (eds) Bawdy Songbooks (2011) III 234: Charon, Pluto’s waterman, will get so cherry merry.
1871		Record (Emerald Hill, SA) 16 Nov. 6/4: If any were cherry, merry, which, looking at the empties I refer to, and hearing of the quantity of Castlemaine Fitz’s sent on to the ground, would not be a very remarkable thing.
1913		Surrey Mirror 23 Dec. n.p.: He was variously described as being ‘freshy,’ ‘cherry merry’ and ‘juiced up’.
1948		F. Foster in Collier’s Wkly 17 Jan. 6/3: Since colonial days, approximately 400 terms to describe being drunk have been used in this country. Among the many no longer heard are bungey, nimptopsical, cherry-merry and ‘as stiff as a ringbolt’.