I Don’t Know Either

There’s this thing that pops into my head every so often.  It’s one of those things that is only dimly-recalled, and I’m not actually certain of the source of it, other than that I’m reasonably certain it was in either a comic strip or a comic book.
Basically, someone keeps doing or saying something that a main character finds bothersome, and this continues over the course of an extended period of time, and it leads the main character to proclaim in frustration, “If X does Y one more time, I don’t know what I’ll do!”
Then it happens again and the main character doesn’t do anything, explaining afterwards that, “I said I didn’t know what I’d do.”
I think it’s from an old Peanuts strip in which some kid kept referring to Snoopy as “fuzzy face,” but, again, I only have the dimmest recollection.
In any case, this springs to mind every so often when I find myself in a similar situation, as I typically end up having the same response.
It’s also related to the whole thing where I think, “I can’t take this anymore!”  And then I take some more.