I like finding obscure references on bumper stickers. The common ones bore me. “Coexist”, “I ♥ my schnauzer”, “Vote for Some Schmuck”, yeah, yeah, we’ve heard it all before. No, I prefer something that takes some thought, off the grid, beyond the pale, outside the box. For example, not long ago I saw one with only the words “Jethro Tull”. Not many people in their younger years (say, 60 or less) would get that. The fact that I did made me feel kind of special, as if I were “in the know”. Here are a couple more. Can you identify the sources?