From the time my mother washed my mouth out with soap – I must have been in first grade or so – until my late teen years, I used no foul language whatsoever. (I did, however, once “make an obscene gesture” to my sixth grade teacher, giving her the finger, god knows why, as I left the school building one day. My Dad asked me whether I knew what “obscene” meant. Of course I lied and said no.)
At any rate, now I swear all the time: alone and in company. I cringe when I do, though, which means that I don’t get that surge of pleasure so savoured by the swearing sort.
So: the habit has got to go.
(To answer your question: It began with a “c.”)