I had no idea who had written the sign, but memories of a relevant lesson still remained rather accessible in my mind. One of the reasons many of us anglos take so long to feel fluent in Hebrew is that we're perfectionists in our grammar and terrified of making stupid mistakes. Unlike English, Hebrew adjectives (and verbs) are supposed to match the gender of the nouns they modify/describe/activate. Frequently my speech slows down while I mentally review all the relevant grammar lessons before finishing a sentence. Native Hebrew speakers take that as a lack of knowledge, sometimes insulting me by using totally awful English in the mistaken belief that my Hebrew is too weak to converse in. The truth is that in some ways my Hebrew is better than theirs.
I defended the grammar in the sign by repeating a lesson I vaguely remembered that all the special "two" endings, -ים -ai'yim like shnayayim 2 years, שנתיים na'alayim, shoes נעליים are feminine. The woman gave me a strange look, as if a "monkey" had given a university lecture.
So, nu, any experts out there?