I think there's definitely a place for it. AC/DC's lyrics, especially with Bon Scott were definitely tongue in cheek. There ar eplenty of metal bands that don't take themselves 100% seriously, and they're better because of it. I saw Hell supporting Saxon once, and the singer's in between patter was side splitting, and made the difference between me thinking their music was OK, to loving them as a band. Wolf Hoffman is hilarious with his onstage grimaces, but I love them, and they are part of what he is. And who doesn't/didn't like Spinal Tap? (showing my age there). And if I may blow my own trumpet ever so slightly, my second novel Cold Steel on the Rocks about a metal band looking for pirate treasure is most definitely chock full of humour.