The phrase "dost a take off" may sound unfamiliar to some, but it is a common expression used in some dialects of English. The spelling can be explained using the International Phonetic Alphabet (IPA). "Dost" is pronounced as /dʌst/ with the "o" being replaced by a "u" sound. "A" is pronounced as /ə/, and "take off" is pronounced as /teɪk ɒf/. Thus, the correct spelling for this phrase is "Dusta take off." It means someone is about to leave quickly.