If there’s one grammatical mistake that riles me it’s misuse of that lovely tool… the apostrophe. I call it the itinerant apostrophe coz it seems to move about a bit! It’s particularly upsetting to see it used where the writer thinks that it’s necessary when talking about plurals of an item. You’ll invariably see it used at a greengrocery when they talk about banana’s meaning multiple bananas. I hadn’t believed that butchers were guilty of the apostrophe crime until I saw this sign indicating that they sold legs of lamb.

You can find out lots more about the use of apostrophes at http://www.grammarbook.com/punctuation/apostro.asp (it’s an American site so you may not wish to trust it!), http://www.oxforddictionaries.com/words/apostrophe (which is of English parentage so it should be trustworthy) or www.apostrophe.org.uk/ (the Apostrophe Protection Society site).