Motörhead, "Overkill"
The oldest and longest-running band at Mayhem Fest, Motorhead's sound is much closer to the acid rock that my parents didn't hate in the late '60s/early '70s. They're also tremendously loud and covered in Iron Crosses, so who knows.
Mom: "Oh, I like the guitar and drums."
Dad: "He's got a better voice." (Whoa.)
Mom: "How can you tell? He's shrieking."
Dad: "Well, at least it's not aggravating like the other two! Wait, is that a Nazi symbol on his guitar?"
*At this point, I consider explaining Lemmy's semi-troubling interest in German WWII militaria, but instead I sort of sheepishly mumble something.*
Dad: "Huh. Their guitars are better than the other guys. They're a lot more musical, I think. Are we done with this one, now?"
RO: Can you do one more?
Dad: "Sure. We've lived with worse. I've listened to Christian praise music, for God's sake."
Mom: "I like Christian praise music!"
Dad: "Yeah, but I don't."