I think that Charlie felt threatened by all of Snoopy's requests for food. It was too much for him to handle When people feel threatened they often respond with anger.
The HEALTHY response would be "Snoopy - you have a hearty appetite. I don't think I will be able to fulfill all of your requests but let's see what I can do for you....." Snoopy would have felt understood and cared for and Charlie wouldn't have lost his temper.
Chazal say [about Moshe's anger in Parshas Matos Pesachim 66] that if one gets angry his wisdom leaves him [חכמתו מסתלקת ממנו]. It is actually a very real physiological reaction that modern science describes:
"Like other emotions, anger is experienced in our bodies as well as in our minds. In fact, there is a complex series of physiological (body) events that occurs as we become angry.
Emotions more or less begin inside two almond-shaped structures in our brains which are called the amygdala. The amygdala is the part of the brain responsible for identifying threats to our well-being, and for sending out an alarm when threats are identified that results in us taking steps to protect ourselves. The amygdala is so efficient at warning us about threats, that it gets us reacting before the cortex (the part of the brain responsible for thought and judgment) is able to check on the reasonableness of our reaction. In other words, our brains are wired in such a way as to influence us to act before we can properly consider the consequences of our actions. This is not an excuse for behaving badly - people can and do control their aggressive impulses and you can too with some practice. Instead, it means that learning to manage anger properly is a skill that has to be learned, instead of something we are born knowing how to do instinctually.
As you become angry your body's muscles tense up. Inside your brain, neurotransmitter chemicals known as catecholamines are released causing you to experience a burst of energy lasting up to several minutes. This burst of energy is behind the common angry desire to take immediate protective action. At the same time your heart rate accelerates, your blood pressure rises, and your rate of breathing increases. Your face may flush as increased blood flow enters your limbs and extremities in preparation for physical action. Your attention narrows and becomes locked onto the target of your anger. Soon you can pay attention to nothing else. In quick succession, additional brain neurotransmitters and hormones (among them adrenaline and noradrenaline) are released which trigger a lasting state of arousal. You're now ready to fight."
Our Avoda, especially during the 9 days, is to catch ourselves before any outburst.
Easier said that done....
[This post was inspired by the uplifting shalshudes drasha of HaRav HaGaon R' Ariel Edelstein Shlita - Shabbos Matos Masei 5776]