“I’m a more or less naïve person, so I’m an experimental artist. I make my way in the dark, you know. I don’t know what I’m doing,” Pink says, but Mature Themes gives listeners a reason to question whether that last statement is true. Stylistically, Mature Themes is all over the place, from the ’70s folk-pop of “Only in My Dreams” to the pure, cascading ’80s electropop of “Pink Slime.” Pink shapeshifts from song to song, delivering his material in the guise of a sort of 1930s “Monster Mash” drone here (“Kinski Assassin”), a child-like Bee Gees falsetto there (“Farewell American Primitive”). The whole enterprise gives the sense of something darkly giddy, just like Frank Zappa and Captain Beefheart did at their best. If Pink keeps it up, he may well land himself in the canon of time-honored outsider artists. Whether he’s able to do that will likely hinge on if he manages to psych himself out too badly before making a couple more great records.