23 March, 2012
Oh wait, here it is! It was hiding on a label for some tea! Mystery solved!
Let's do a refresher, shall we? If a word is a contraction of two words (Let's for "let us" or something's for "something is", then it gets an apostrophe. If a word is a plural (two or more of something; one hundred monkeys, a plate of tacos), it does not.
Plurals: No apostrophe
All clear? Now, go forth and erroneously punctuate no more!