t.t.f.n., phr. — Green’s Dictionary of Slang

t.t.f.n. phr.

[ta-ta for now, orig. created and popularized on comedian Tommy Handley’s BBC Radio show ITMA (It’s That Man Again, 1939–49). Dorothy Summers, as ‘Mrs Mopp’ (the comic charlady) actually used the phr., which was revived by BBC Radio 2 disc jockey Jimmy Young (b.1923)]

goodbye.

1944		A. Morrison letter 22 Feb. in Morrison Things My Mother Never Told Me (2002) 93: TTFN. DILY. DDYLM.
1998		Eble Campus Sl. Apr. 10: t.t.f.n. – good bye.
2003		McGill Reed Dict. of N.Z. Sl.