TTFN is an initialism for a colloquial valediction, 'ta ta for now', based on 'ta ta', an informal 'goodbye', approximately equivalent to 'bye bye', 'see ya' or 'laters'. The expression came to prominence, in the UK, during the Second World War.
TTFN is still used occasionally in ham radio as an ending to a transmission but was brought into popular use in the UK in 1941 in the weekly radio comedy ITMA by the character Mrs Mopp. From 1939, initialisms, previously rarely used except by the military, were heard more frequently by the British public. ITMA satirized them by coining TTFN, a "pointless" initialism (no easier to say than the phrase on which it was based) and using it as a catchphrase.
TTFN is frequently used in The New Adventures of Winnie the Pooh by Tigger, often followed by a "hoo hoo hoo hoo!" as he bounces away on his tail made out of springs. Tigger's profound over-usage of the colloquialism ushered in a new era of TTFN users, primarily young U.S. adults who watched Disney Channel as children.
'Ta ta for now' caught on with the British public so much that it was often uttered by dying people as their last words.[1]
It was a catchphrase of Jimmy Young, a BBC Radio disc jockey and entertainer from 1967, until he retired in 2001.[2]
It also appears in The Vampire Diaries and Buffy the Vampire Slayer (TV series).