This sign is posted at a university gym. This is another one of those signs that you just know must have an interesting history. (This is something I point out to my business students: any regulation has a history, and it’s worth pausing to consider just what that history might be, what conflict led to the rule, etc.)
Also interesting that they’re appealing to health concerns, here, rather than to basic etiquette. (How likely is it that the health claim made here is based on anything like hard evidence?)
Thanks to Joe Desjardins for the photo.