Normative Signs: The Poetry of "Ought"

Two things come to mind with regard to this straightforward sign.

1) It seems like a perfectly reasonable request—provided you have a clear understanding of what “foreign” means in this context.

2) What’s the story here? What’s the history? What were people flushing (no, I don’t *really* want to know) that inspired officials to print and post this sign? (My constant theme: every sign, like every government regulation, has a history.)

Thanks to Charles for contributing this image (which is from an office building of Canada’s federal government).