“Macky’s been a bad, bad boy,” Mac DeMarco declares on his second album. Glance around the Internet, and you can see why: The 23-year-old Montreal indie rocker loves to get naked, smoke and crossdress. It’d be easy to write him off as another product of Generation Selfie. But Salad Days is packed with wry, knowing lyrics and washed-out vocals, like a meeting of Stephen Malkmus and Marc Bolan. On “Let My Baby Stay,” he ruminates on relationship paranoia, and “Brother” philosophically urges you to “let it go” over groovy, pot-fueled guitars – it’s slacker rock that (sort of) has a message.