"Round our house, It's "The Firetruck Word."F words.
Back in late elementary school, DS asked me, with a totally innocent face, what word started started with f and ended in ###. I was about to wash his mouth out with soap when he informed me that it was "firetruck," then started giggling like a maniac. I should have washed his mouth out with soap, anyway, simply for knowing what the other word was, but I was too shocked (and relieved) and laughing along with him. The word stuck and years later, we still use it. It doesn't happen very often, but when someone around here starts (literally) muttering "Firetruck," we all pay attention. Once the muttering starts, ya never know what's coming, next and we may need to know whether to be a good listener ... or a fast runner!