Some thought the CERN hadron collider would create a black hole that would engulf the Earth. Turns out, it was a "single-use restroom" that would be our undoing.
I think it's supposed to be "Single User" to indicate it is a one-toilet, gender-neutral bathroom. It is also meant to indicate that it is handicapped-accessible (but not preclude helpers). But, the sign and message are a mess.