Humor and irony, both, significantly rest upon the interpretation of the listener or reader, as they mostly dwell in the realm of subtext that relies on shared knowledge or understanding. In the sentence, "When she's hungry and not being herself: D Xickers", the humor and irony are centered mainly on the premise of someone behaving differently when they're hungry and how this behavior change is being attributed to a fictional character 'D Xickers'.
Humor can be derived from the incongruity theory, which states that people find humor in situations where there is a conflict between what should be and what is; between expectations and reality. The average reader would perceive a gap between regular behavior of a person and their behavior when they're hungry (reality). The humorous twist is the coined term 'D Xickers', which serves as an amusing excuse for the behavior change. It's like saying, as a joke, that she transforms into this made-up character when she's hungry.
The irony is found in situational irony. It brings to mind a contrast between what is expected (someone acting rationally) and what happens (excessive mood swings/poor behavior) when someone is hungry. Also, it's slightly ironic that, hunger, a basic human necessity, has the power to change someone's behavior to an extent where they are almost 'not themselves', reflecting the paradoxical nature of human behavior and needs.
The sentence also features a comedic trope widely used in media, where characters turn into completely different personas when they are hungry, such as the snickers commercial catchphrase “You’re not you when you’re hungry”. This could be viewed as an implicit reference to these kinds of comedic tropes, which again adds a layer of humor.
There's an element of absurdity in the sentence, which is inherently comical. The notion that hunger can change a person so drastically that they assume a different persona (D Xickers) is absurd in its exaggeration. The humor emerges from this absurdity, as it is unexpected and ludicrous.
In sum, the humor in this sentence hinges on the absurdity, ironical situations, and the unexpected incongruity between a person's usual behavior and their behavior while hungry. The sentence uses exaggeration and references to a fictional character as comedic mechanisms to highlight these differences, making it a humorously ironic remark about human behavior and its surprising malleability in the face of hunger. When she s hungry and not being herself D Xickers