The Smiths and Mr Bungle wouldn't exist (lyrically anyway) if there wasn't room for humour in music. And that, to me, would be a Very Bad Thing. However, I cannae be arsed with lyrics that try too hard to be funny. As mentioned by someone, they always fail. The dry wit of Morrissey and absurdism of some of Patton's lyrics are great, but most attempts at humour (usually by American bands to be honest) are just terrible. I also cannae be arsed with the attempts at non-lyrical humour by American bands, eg when Kurt Cobain used to act the goat. It wasn't funny, he just looked like he was trying to be funny, and was failing. Most Foo Fighter's videos are examples of that too, although sometimes they can be slightly mirthsome for the first couple of times.