I also think that "playing startup" is so obvious that many people could have come up with it. That being said, it's also quite possible that I saw it somewhere and absorbed it without fully remembering the source and now have a false memory of coming up with it myself.
I will add though that it's pretty fascinating as someone who is so disinterested in (and at times has a disdain for) startup people and startup culture, to be accused along the lines of, "how dare you feign not knowing who Startup Person X is!"