A personal favourite of mine. There's something more profoundly satisfying about a professionally produced apostrophe error than a hastily hand-written blunder. Really.

From Greek Peak ski resort in upstate New York. Home of skier's, snowboarder's and other thing's ending in s

This just in, from one of our "officer's" in TX. Seen at a Freebird World Burrito restaurant in Round Rock. A beautiful creation.

Don't keep me in suspense. Your 9" tomato pie is what?

I tried really hard to make this work on some weird grammatical level, but I just couldn't. A crime like this is made all the more grave by the fact that these were stuck on all the copies of this particular edition of the USA TODAY newspaper. Fortunately, their readership has dropped in recent times, so only 7 people got to see this filth.

Me: "Is Sport here?"
Shop assistant: "What?"

Case closed. Guilty of construction of an invalid plural noun. Adjourned for sentencing.

Offence committed in San Diego

I love a panini as much as the next man. I have even been known to have two paninis in one sitting. I don't know if I have ever eaten "panini's" though. Taken on the upper east side of NYC. Guy in the reflection got all funny with me for taking a photo of "his" building.