And the award for Most Unnecessary Signage goes to...

This. As Rain Noe perfectly explains on Core77, "the entire point of [the two symbols] is that they don't require an explanation and can be understood by those who cannot read English." The complicated clarifications, filled with text of three different sizes and styles and variable underlining, ruin a simple and effective design. I'll be so lost in puzzling over all this that I might just ignore the steady red hand and wander into the street!
[Core77]

Emergency-alert buttons should be unpressable!

Recently, poor UI design led to a false incoming-missile alert in Hawaii. This is a terrifying accident - and a failure not of the user, but of design. According to reports, the alert was in the same drop-down menu as test alerts used regularly for various internal purposes; the addition of an "Are you sure?" dialog box didn't help, since most people cruise through dozens of those every day. Buttons with serious consequences really should be unpressable - it should take unusual thought or action to press them. These kinds of designs already exist at all levels; examples from severe to mundane include the classic "turn two keys at once" to launch a missile, "break glass" to pull a fire alarm, the recessed "panic" button on your car keys, even the slightly-longer press required to engage caps lock on a Mac. I hear the employee who pressed the button has been reassigned - but the designer of this button is truly at fault.