A moronic, poorly used English phrase, meaning: I'm getting ready to do (whatever the task may be), or I am preparing for something. Normally used by common hicks from the south, often those who have betrayed their fiances...
Getting ready to (do something). Pronounced "fixin ta" or when contracted further "finna". There are phonemes not used in standard American English in these pronunciations so these translations are not completely accurate. Often thought to be limited to Southern white speakers (fixin' to) or African American speakers (finna) the phrase has made it into Standard American speech as "fixing to".