(Britain, Ireland, Canada, Australia, New Zealand, South Africa) Said on the first day of a new month, while pinching and punching someone as a prank (especially by children). The victim may respond with "a flick and a kick for being so quick" and the original attacker may reply with "a punch in the eye for being so sly".
(Britain, Ireland, Australia, New Zealand) More generally, a pair of attacks or setbacks at the start of something.
Source: en.wiktionary.org