The correct spelling of the phrase "gat back shape" is actually "get back in shape". The misheard version likely results from similar-sounding phonemes in English. In IPA phonetic transcription, "get" would be /ɡɛt/, "back" would be /bæk/, "in" would be /ɪn/, and "shape" would be /ʃeɪp/. It's important to double-check spellings to ensure effective communication, whether written or spoken.