A speaker eats ice and imagines what it will do to the body: the belly will swell, and the swelling will become something bigger than a simple stomach. The title, "Glutton for punishment," gives the scene a wry edge. Eating ice is a cold, slightly uncomfortable thing to do, and the speaker seems to choose it anyway, almost greedily.
The strange part is the image of the belly growing "dangerous as / a great master." A master suggests authority, skill, maybe a teacher or a ruler, and the word "dangerous" makes that power feel a little threatening. The last line, "exceeding every me," hints that the speaker contains many versions of themselves, and that this one appetite will outgrow all of them.
The mood is playful but uneasy. There's dark humor in treating a cold snack as something momentous, yet the poem also suggests that our own hungers can take over. The short lines and sudden stop leave that thought hanging, like a chill that lingers after you swallow.