Dave Bonta's "Wet" is only a few words long, but it holds a small, quiet idea. The speaker is on a full bus on a rainy day, surrounded by other people, and feels almost invisible. In a crowd like that, no one looks closely at anyone else. Everyone is damp, tired, and focused on getting somewhere.
The last line is the clever part. "Incognito for the rain" can be read two ways. The rain might be the thing the speaker is hiding from, or it might be the cover that makes hiding possible. Wet coats, steamed-up windows, and lowered umbrellas all help a person disappear. I think the second reading fits best, since the speaker sounds more relieved than bothered.
The mood is calm and a little wry. There's a sense of private comfort in being anonymous among strangers, as if the bad weather has given the speaker permission to be left alone. It's a tiny, ordinary moment, noticed and kept.