Are you really you when you're hungry? What makes someone go from simply being hungry to full-on 'hangry'? More than just a simple drop in blood sugar, this combination of hunger and anger may be a complicated emotional response involving an interplay of biology, personality and environmental cues. Source 8b.
While I have never experienced a person who was actually "Hangry" I have met a few people who stated they were getting to the point of being hangry. I think this new word of hangry is just a metaphor for many people with those that actually do get hangry are few and that could be a condition they grew up with as a way to get food so they were not hungry anymore. I would take this more as a learned response than just something people throw around to get attention at times.
Link between hunger and mood explained. The study used rats to examine the impact on emotional behavior of a sudden drop in blood sugar. When the rats were given a glucose blocker, researchers found they had higher levels of cortisol. They also showed signs of stress and sluggish behavior similar to a poor mood. To prove the behavior wasn't just a lack of glucose to the muscles, researchers then gave them a common antidepressant and the behavior disappeared. Source 5v.