Its basic job is joining alternatives, as in the last line, where you type one thing or another. But seven of the eight lines here show it inside 다거나, the version that floats hypothetical examples rather than offering a real choice: your skin breaking out or growing horns, people looking low on energy, someone having put salt in it. Read those as things like this, for instance, not as a genuine either-or. For a plain choice between two nouns, Korean normally uses 이나.