"Welcome to the 60's" what?

So, I finally saw Hairspray this week. The Broadway show, I mean, not the movie, nor the other movie. And it's entirely my own fault that it took me so long to get to the theatre to see this popular show that there are now not one but two Hairspray movies I haven't seen. Anyway, I'm not going to talk about the whole show, which you've probably seen already anyway. I just want to talk about one small part: the scene-change-accomodating reprise of "Welcome to the '60s." There I am, enjoying the show after a long day spent copyediting. The Dynamites, the show's black girl-group chorus, step forward and take turns riffing on the song's title, and one of them sings assertively: "Six! O! Apostrophe! S!"

You don't need me to explain why that made me cringe, do you? Somebody please tell me that actress was just ad-libbing. Tell me her part hasn't been written out that way, and performed that way, for the past five-plus years. Because I don't want to believe that the placement of the apostrophe is correct in the Playbill's listing of songs, but wrong in the actual lyrics. Don't MAKE me give you a lecture on the appropriate use of apostrophes, Marc Shaiman and Scott Wittman. Because I WILL.