Submitter Susan adds that "This sign comes from a gun club (a clubhouse for men with guns who like to drink beer in the woods) in Northeastern PA." This is classic. I think there are quotation marks around "when leaving party" because, I mean, if you're that fun, you ARE the party - so you never leave it. Also, the duct tape holding it up is a nice detail.
I don't usually post the following: newspaper headlines, personal email, craigslist postings, unprofessional websites. I also tend to not crosspost things from other blogs, since I have so much unique material waiting for me to get to it.
Things I see a lot: silica gel "do not eat"; hair dryer labels; inside the bus "do not drill"; Wal-mart sign about IDs; coffee machine with "2" cup sizes; employees must "wash hands".