Why Do We Say “Rabbit Rabbit” Each New Month?
What does rabbit rabbit mean?
Though it sounds a bit like gibberish, the phrase rabbit rabbit is a long-held superstition thought to bring about good luck. But it’s not to be uttered just any old random day. Rather, if you say it on the first day of the month before any other words come out of your mouth, then luck is thought to be coaxed your way. If you get your rabbits in, luck is yours for 30 days … or so goes the folklore.
https://www.dictionary.com/e/rabbit-rabbit-and-hare-hare/