I have never actually put soap in his mouth, and have only used that threat once in his entire life.
He told us he was just preparing because he had a feeling he was going to get angry at me tomorrow, and say a bad word.
I heard Michael in the carseat.....what's the word?......salivating/making spit and then doing that annoying sucking sound to keep the spit in. (How would you explain it?)
After hearing it over and over, I asked "What are you doing?"
Michael replied, "I'm thirsty, so I'm drinking my spit!"