I need help her gals.
"Then he asked if sticking up his middle toe was bad"
I don't remember why he did it, I was just focused on that he did it
Why did he say he did it?
Was he upset with something you or his father (or this other mom) said or did? Was he trying to get a laugh from the other kids? This might sound strange but did he use it "right"? In other word does he understand what it means and when its used? Part of my response would be based on why he did it. If he was my child he still would be in a lot of trouble but knowing the why would help me determine what else might needed to be done so it wouldn't happen again any time soon.
What was his punishment the previous times? How long was it between each use?
We had a bad word jar for a while. Any time a bad word was used 50 cents went into the jar. At the end of the year (or if filled) that money was donated to charity. But I don't know how much help that would be especially as my kids still think words like stupid are really bad words. In fact Philip(9) came over upset earlier to tell me his sister said the S word and didn't want to even whisper it to me. I'm trying to get him to understand that it isn't a nice word to use but its not in the same catergory of other more offensive words.
I would be tempted to tell him that he would no longer be allowed to hang out with other kids away from me because he can not be trusted to behave himself. I don't know if that would work long term though. hmm...