Also known as little man syndrome or lms. When a small guy tries to be tough because he's shorter than average or small of stature. (Taken from the name Napoleon, who was just a few inches over 5 feet tall and tended to blow people up and start wars.) See Napoleonic War.
Rick had a case of napoleonism beacuse he was only 5'5". He didn't need to be so tough, 'cause he was a great and kind friend who would do anything for you. Unfortunately, people still look down upon short people, and he took this personally.