The speaker talks to their own mouth as if it were a guest being summoned to a table, or even a piece of goods being put up for sale. "To dinner I sell my mouth" is a strange, slightly comic line: the mouth is both the thing that eats and the thing being handed over. The parenthetical "and a little supper" reads like a quick afterthought, a bargain-stall add-on.
The tone is playful and a bit giddy. The repeated "to dinner" feels like a chant or a call to the table, and the speaker seems eager, even greedy, in a cheerful way. The last lines turn the invitation into a kind of honor: the mouth should live "for the honor of the open mouth." That phrase could mean hunger, appetite, or speech. The poem doesn't say which, and that ambiguity is part of its charm. Overall it creates a mood of appetite, mischief, and delight in the body's simple pleasures.