Saying "rabbit rabbit rabbit" first thing before you say anything else aloud on the first day of a new month will bring good luck that month.

I picked this up in elementary school from reading the Baby-Sitters Club Little Sister books by Ann M. Martin, which I realized even at the time was a silly place to pick up superstitions. But I still do it when I remember. More often I'll realize too late "Damn! It's been November 1 for an hour and a half and I've been talking the whole time!"