I don't know when I first heard it - but for a lot of years '
Rabbit' has been the first word out of my mouth on the first day of the month. . . when I remember!  It's supposed to bring you luck for the rest of the month!
Our daughters loved the tradition and would often say 
Rabbit themselves.  They would ask me where this came from - and honestly - I didn't know.  But thinking about it yesterday - as I said 
Rabbit to myself while sitting in the recliner in the wee hours of the morning (I woke up with a whopper of a headache), I decided to see if it was something I had just made up, or if it really was handed down from somewhere else.
Wikipedia says this:  
The exact origin of the superstition is unknown, though it was recorded in 
Notes and Queries as being said by children in 1909:
"My two daughters are in the habit of saying 'Rabbits!' on the first 
day of each month. The word must be spoken aloud, and be the first word 
said in the month. It brings luck for that month. Other children, I 
find, use the same formula."[1]
Yankee Magazine says:
Today is the first day of the month and Rabbit! was the first word 
spoken in this house. I grew up thinking that our family was the only 
family with this strange tradition. On the morning of the first day of 
every month, there was a slow chorus in our house, from room to room, 
the word “Rabbit” was spoken one and then another until we had all been 
granted our month’s worth of good luck. In my mind, my grandmother was 
the originator of the tradition, and it extended to all my aunts and 
uncles and cousins on my father’s side of the family. My mother was 
complicit so I didn’t realize it was not her tradition, growing up, but 
rather something she adopted once she married my father. The 
superstition was that if you forgot to say rabbit, spoken as the first 
word on the first day of the month, you would have bad luck that month. 
Now that I have written that down, I realize how spooky it sounds, as if
 we were a bunch of paleolithic cave people, clinging to the earth by 
virtue of luck and whimsy. Whenever I mentioned this custom to friends, 
they would usually ask me where that came from. My only answer was “from
 my grandmother,” which, of course, is the short answer. Beyond that, I 
had no idea.
Yahoo:
Rabbit rabbit" is a common British superstition. The most common modern 
version states that a person should say "rabbit, rabbit, white rabbit", 
"rabbit, rabbit, rabbit", "rabbits, rabbits, rabbits",[1] "rabbit, 
rabbit" or simply "white rabbits" upon waking on the first day of each 
new month, and on doing so will receive good luck for the duration of 
that month. In the United States, the tradition is especially common in 
Nantucket, Cape Cod other towns within Massachusetts and Chester 
Vermont. 
However, some reports place its origins even earlier, into the 1800s. 
Today it has spread to most of the English-speaking countries of the 
world, although, like all folklore, determining its exact area of 
distribution is difficult. This superstition is related to the broader 
belief in the rabbit or hare being a "lucky" animal, as exhibited in the
 practice of carrying a rabbit's foot for luck. Some have also believed 
it represents jumping into the future and moving ahead with life and 
happiness.
So - if you haven't been a fan of 'Rabbit' up to this point - may you speak it first on the first of each month and enjoy good luck!
Happy February!