On a recent Sunday evening, comedian Dan Swartwout — wearing a T-shirt and blue jeans — told the audience at the Funny Bone Comedy Club at Easton Town Center that he was a virgin until he was 23.

Not everybody is into Steely Dan. John Mulaney, however, is a huge Steely Fan. He’s been trying to spread the Steely Dan gospel for years now, whether he’s bringing his younger friends to ...