I'm not sure it's involuntary or weird, but I come from a household where no one swore, all through my childhood and adolescence. And then in my first week at university I met someone who is still one of my best friends, from a VERY well spoken, very typical English village background (father an author, lived in thatched cottage in a village in Sussex), and I was amazed (and, I have to say, influenced) by the way she would walk in a small circle in her room when annoyed and mutter "Piss, shit, knickers, fuck" repeatedly until she'd got it out of her system.
More recently my husband and I have adopted Malcolm Tucker from "The Thick of It" on television and his "Come the fuck in or fuck the fuck off" approach to life.