 A variant of the phrase — " have a good day " — is first recorded in Layamon 's Brut ( c . 1205 ) and King Horn . " Have a nice day " itself first appeared in the 1948 film A Letter to Three Wives . The phrase was subsequently popularized by truck drivers talking on CB radios . Variations on the phrase include " have a good one " and " have a nice one " . In conjunction with the smiley face , the phrase became a defining cultural emblem of the 1970s and was a key theme in the 1991 film My Own Private Idaho . By 2000 , " have a nice day " and " have a good day " were taken metaphorically , synonymous with the parting phrase " goodbye " . 
