Green’s Dictionary of Slang

extremely, very much, var. on damnably adv.

1927		E. Hemingway letter c.15 Sept. in Baker Sel. Letters (1981) 261: Got a sheet to fill out from Who’s Who and my life has been so fuckingly complicated that I was only able to answer two of the questions.
1952		G. Legman The Limerick (1969) 47: The skater, Barbara Ann Scott / Is so fuckingly ‘winsome’ a snot, / That when posed on her toes / She elaborately shows / Teeth, fat ass, titties and twat.
2003		Mr John ‘Article 100’ on teamfishcake.co.uk 🌐 This first article for my newly stolen Team Fish-cohorts was fuckingly shit.