You're making me think about it, and it's really tough. I think "Birdhouse" wins for me for its lyricism and allusions, but "Hearing Aid" and "Lucky Ball & Chain" are probably tied for a close second. I also really like "Women & Men." What about you?

In terms of "What do you find yourself spontaneously singing around the house?", Lucky Ball & Chain, Minimum Wage, We Want A Rock, and Whistling in the Dark are all strong contenders.