Q. Dear Twig: I have a question about the words that my sister and I sing to "Jingle Bells." Why does Batman smell?
A.: Science has yet to study the question. So one can only guess. Batman might have bromidrosis ("bro-mih-DRO-sis"), also called body odor. (Oh? "No! B.O.!" Oh.)
See, Batman's job has mental stress and also plenty of physical work. Both can make the human body sweat. Especially a body that has gone through puberty (the medical name for the process of changing from a child into an adult). (Which Batman, based on his name, has done. If not, he'd be Batboy.)
But if the sweat stays on the body awhile, even if only a couple of hours, bacteria start to break the sweat down. Ammonia and short-chain fatty acids result. Both can reek. Gaaa!
The solution is usually just simple good hygiene ("hi-jeen"): washing one's self clean.
Batman might just need a bath!
P.S. His costume could do it, too. Polyester fabric holds odors. Batman came before spandex!
Notes: Regarding the rest of the folkloric lyrics: Robin can't lay an egg. He's a male human, not a female bird. Regardless, ovulation by robins, at least by the robin species that live and breed in the Northern Hemisphere (the presumptive location of Gotham City), takes place in spring and summer, not December, the typical time for this vocalization. The Batmobile might have lost a wheel due to insufficient lug-nut torque. The Joker might have run away due to Batman's alleged bromidrosis or, perhaps, to wanting to be a dentist, which, as Sam the Snowman tells us, never solves anything, unless the problem is that someone near you has bromidrosis. Bromidrosis is sometimes spelled "bromhidrosis."
"Smart Stuff with Twig Walkingstick," published by The Ohio State University College of Food, Agricultural, and Environmental Sciences - specifically, by the Ohio Agricultural Research and Development Center (OARDC) and Ohio State University Extension, the research and outreach arms, respectively, of the College - is a weekly column for children about science, nature, farming and the environment. It's written at a 4th-grade reading level. For details, to ask Twig a question, and/or to receive the column free by mail or e-mail, contact Kurt Knebusch, CommTech, OSU/OARDC,1680 Madison Ave., Wooster, OH 44691, firstname.lastname@example.org, (330) 263-3776. Online at http://extension.osu.edu/~news/archive.php?series=science.