Green’s Dictionary of Slang

1. euph. for Christ! excl.

1928

Strand Mag. July 70/1 306: You’ve saved your man, by crimbo [OED].

2. Christmas.

1966		P. Moloney Plea for Mersey 63: Dick Crimbo – St. Nicholas.
1996		J. O’Connor in Irish Male: His greatest Hits (2009) 178: Your friends, whom you have not seen since last Crimbo [...] have decided that it is your turn to have them over for ‘supper’ .
2010		Eve. Standard 20 Dec. 21/4: [headline] ...but here’s someone who can’t get enough of Crimbo.

3. attrib. use of sense 1.

1989		Looks Dec. 5: Worth cancelling a crimbo party to catch this one, it’s totally fab [OED].
1998		K. Sampson Awaydays 88: Just down the road, the united might of the Birkenhead Civil Services are holding their annual Chrimbo bash.
1999		Guardian Rev. 27 Aug. 19: Christmas presents are ‘Crimbo prezzies’.
2000		P. Howard Miseducation of Ross O’Carroll-Kelly (2004) 18: The old Crimbo report comes and I ended up failing, like, six of my seven exams.
2006		C. Marriner Southern Style 7: Touched down at 6 a.m. Crimbo morning.
2007		R. Milward Apples (2023) 97: [T] Crimbo lights illuminatinfg the nutcases.