The whole poem is a single twist on a familiar phrase. We say "the crack of dawn" for the very earliest light of morning, the hour when keen, disciplined people supposedly rise. Here, the speaker swaps in "noon," and the result is a small joke: getting up at midday, when most of the day is already gone.
The line breaks help the humor land. "Getting up / at the crack" sounds like the start of a virtuous, early-riser sentence, and then "of noon" pulls the rug out. The pause before that last line works like a comic beat.
As for the speaker, they seem relaxed and a little cheeky, maybe even proud of their laziness. There's no guilt in the tone. The mood is light, playful, and lazy in the pleasant sense, like a shrug. The poem is tiny, but it gently pokes fun at our habit of treating early rising as a sign of virtue.