BTO might have been the laziest band I ever saw - well, them and Foghat. I didn't particularly care for either one of them, but in those days we'd see any band that came to town. I don't even remember BTO they were so lacking in anything even remotely memorable, and Foghat - they came on stage in god damn sweat pants. Like a bunch of dudes going to get milk and diapers on Sunday morning.
But both of them were like whirling dervishes though compared to the grateful dead, who, for all intents and purposes really could have been dead the night I saw them. So they remain firmly and eternally at the top of the laziest bands I've ever seen list.
I make a distinction between boring and lazy here, because I saw a million boring bands, but at least most of them tried.