To a certain subset of the millennial generation—those of us who can still distinctly remember the screech of a dial-up internet but also don't quite recall never having an iPhone—Hulu's PEN15 is going to be, as we used to say on AIM, 2Real4U. Created by Maya Erskine and Anna Konkle with The Lonely Island's Andy Samberg, Akiva Schaffer, and Jorma Taccone onboard as executive producers, the 10-episode series stars Erskine and Konkle playing seventh-grade versions of themselves surrounded by real grade-school actors. But that's never a gimmick. It never devolves …