SAN FRANCISCO (CBS SF) — Social commentary full of satirical whimsy is popping up in the form of official-looking signage near a touristy part of San Francisco.

A sign that reads “No Tech Zone” with a red line stuck across a smart device will make you blink twice as you question its authenticity.

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After all, it blends in with all the other official signs that have San Francisco Recreation and Park Department stamped at the bottom.

Several people posted images of the sign posted near Alamo Square last week.

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“No cell phones, tablets, laptops or smart devices permitted,” the sign says with this hefty warning: “Violators subject to $300 fine.”

San Francisco Recreation and Park Department spokeswoman Connie Chan says the signs were not put up by any city agency.

In a city known for frequent animosity between long-time residents and newly-rich techies, perhaps the prank hits a bit too close to home.

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Nicole Jones is a digital producer for CBS San Francisco. Follow her musings @nicjonestweets