To all the writing geeks out there who freak out over when someone uses "it's" instead of "its", well, today is your day. September 24 marks National Punctuation Day. Grammar geeks, feel free to point out any unnecessary commas, extra apostrophes, and misuses of emdashes and endashes — here or elsewhere. To celebrate, this post is riddled with a few mistakes for the editor in you. Point out our errant semicolons, debate our usage of the Oxford comma; and maybe get a little angry over unnecessary spaces ( please keep an eye out on Facebook for these offenders ) . Our apologies, if this is hurting your eyes — its hurting our writers conscience, as well. Meanwhile, this nifty quiz from Northern Illinois University lets you test your punctuation skills in 11 quick questions. How well did you do? Let us know in the comments below.