could be raining.
There could be snakes.
Okay, this is totally off-topic, but has anyone read James Stevenson's children's books? He's most famous as a New Yorker cartoonist, but he had a series of beautifully watercolored picture books when I was little that I loved. (The connection here is that my favorite was called "Could Be Worse!," which is sadly out of print.) Anyone else remember these?