found this on Wikipedia;
A commonly related story says that the song's title was originally "In The Garden Of Eden" but at one point in the course of rehearsing and recording, singer Doug Ingle
got intoxicated and slurred the words, creating the mondegreen
that stuck as the title. However, the liner notes on 'the best of' CD compilation state that drummer Ron Bushy
was listening to the track through headphones, and couldn't clearly distinguish what Doug Ingle answered when Ron asked him for the title of the song (which was originally "In-The-Garden-Of-Eden"). An alternate explanation, as given in the liner notes of the 1995
re-release of the In-A-Gadda-Da-Vida album
, is that Ingle was drunk and/or high when he first told Bushy the title, and Bushy wrote it down. Bushy then showed Ingle what he had written, and the slurred title stuck."
Brand New Man - Brooks & Dunn