Literally, the couplet means that when the days of fasting arrive, we too will long to go among the children and drink wine.

This couplet is a brilliant portrayal of human contradiction and the struggle between discipline and indulgence. The speaker, while acknowledging the necessity of religious observance (fasting), immediately undercuts that resolve. The lines suggest that no matter how much one tries to control their vices, the temptation—the sheer joy of life's pleasures—will inevitably pull them back. It is a deeply relatable confession about the limits of human will, delivered with a wry, self-deprecating humor.