Redwood City, CA has actual, printed signs scattered around that say things like:

“Traffic school is boring. Slow down.” “Speed limit 25 mph. It really won’t hurt.” “Is today the day your speed hurts a child?” “In a hurry? A speeding ticket will make you late!” “What don’t you understand about 25 mph?”

and maybe a dozen more. They’re actually great indicators that the city doesn’t enforce the speed limits. Which makes the “ZERO TOLERANCE” speed sign the funniest one.

Edit: The city of Hayward, CA has a pedestrian crossing sign that says something to the effect of “Heads up! Cross the street, THEN update Facebook.”

Signs are cheaper than properly-designed roads. They're safety theatre, designed to make people feel better without actually doing anything.

I saw an interesting sign in Hyderabad saying "Think! Talking on Cell Phone while driving may pave the way to hell." It had Yama, lord of death talking to a driver on the phone and welcoming him. Photo: https://photos.app.goo.gl/FrWaV356DXfjCjWj8

Another of my favourites was the simple "Better Late than Never".

Missing the all-time classic "Speed Thrills But Kills".

West Bengal is even better. One year they had "Save Drive Safe Life". The next year some one in state transport department realized the error and it was "Safe Drive Save Life"

I've seen a sign (in the US) with three messages in eternal rotation:

YOU LOSE

YOU DRINK

YOU DRIVE

ah, the good old "left is right, and right is wrong" to ponder about on a 19-hour drive to Ladakh...