Bliss's "Snake" is a short, silly story about waking up with a snake on your head. Instead of panicking, the speaker simply asks what it's doing there, and the snake throws the question straight back. The speaker answers like a stubborn child, "I asked you first!", and the snake, offended, slides down to cover his eyes. He tumbles out of bed, and the fall hurts.
The tone is playful and deadpan. A strange event is treated as an ordinary argument, and the bouncy rhymes ("head" and "said," "first" and "worst") make it feel like a nursery rhyme or a joke. Still, the speaker ends up in real pain, with a head that feels "angry" and "bathed in agony," so the humor has a sore edge.
The last two lines repeat the opening almost exactly, which suggests the whole thing starts again. The mood is comic but a little eerie, like a dream or a loop you can't escape.