"Hashtag"

       Since it was entered as a new word in the Oxford English Dictionary this month, June 2014, I suppose I should try to be a little less benighted than the Zits parents:

click on cartoon to enlarge

     
       Wikipedia tells me Chris Messina proposed the use of the symbol to tag topics of interest on Twitter on August 23, 2007.   The first use of the term "hash tag" was in a blog post by Steve Boyd three days later on August 26th.  A not so secondary sidenote is that in 2010 on its front page Twitter introduced "Trending Topics," displaying hashtags that were rapidly becoming popular.

       By the way, If I'd been one of the Zits parents (and I am), I would have said, "Tic Tac Toe?"