The one on the left below is from the city of Bangalore. It took me a while to decipher the cryptic message, until a burly man with black oil on his hands and face walked up to me and said, "Sir, you want puncher work or wallkenosing, we are experts. Just tell us what you want to do, and we do it for you!"
No, he wasn't offering to punch some one's nose for me - he was looking at the tyres of my car as he spoke, and it dawned on me that he was speaking of 'vulcanising' and 'fixing punctures'.
This one's from Canada
The picture on the right is one that I took in the Royal Kennebecasis Yacht Club, Rothesay, NB, Canada. The confusion between you're and your is a common one around the world. I think the reason is simply that they are homophones.
Read "Eats Shoots and Leaves" by Lynne Truss