You know, I didn't quite see it first, but I thjink Ann Althouse really is on to something with this ad. I'm a writer (I'd like to think of myself as one), so I usually pick up on these things. I'm not sure if I was just being lazy, or what, but the carrot vs onion rings sexual imagery fits.
Oh, and I guess the carrot really is a phallic symbol. Nothing like those masturbation stories, huh? Thanks, Google!