Time travel
This sign is perhaps the most recent one on the list – it was spotted at the San Francisco protest this September. Seems like this guy wasn’t too concerned about the social issue, though, as he had a different pressing matter on his mind – time travel.
In case you need an explanation of the joke – when referring to time travel, it’s irrelevant to mention a specific period, since you can travel to any time you want. This is a very pressing matter for more people than you might have thought.