I don't actually know much Yiddish, although for the purposes of this problem of diane's, "OY VEY!" might be appropriate, and although not real Yiddish, "VHAT THE HECK ARE YOU THINKING?" would work too.
When my brother and I were kids, we just assumed you naturally learned Yiddish when you grew old, because all the grandparents spoke it.
I'm glad you don't feel guilty for derailing the thread. There are those who come here for advice, and then don't want to listen. You are right, she won't get any better answers in her new thread.
Oh, who told you I was Jewish anyway? I sure hope it wasn't....zee Germans....