From Teen Vogue: We Need to Talk About Digital Blackface in Reaction GIFs: Why is it so common?" by Lauren Michele Jackson.
A good discussion of how racist stereotypes about black people play into and are reinforced by the use of GIFs of black people to represent strong emotions. Short quote under the cut:
After all, our culture frequently associates black people with excessive behaviors, regardless of the behavior at hand. Black women will often be accused of yelling when we haven’t so much as raised our voice. Officer Darren Wilson perceived a teenage Michael Brown as a hulking “demon” and a young black girl who remained still was flipped and dragged across a classroom by deputy Ben Fields. It's an implication that points toward a strange way of thinking: When we do nothing, we’re doing something, and when we do anything, our behavior is considered "extreme." This includes displays of emotion stereotyped as excessive: so happy, so sassy, so ghetto, so loud. In television and film, our dial is on 10 all the time — rarely are black characters afforded subtle traits or feelings. Scholar Sianne Ngai uses the word “animatedness” to describe our cultural propensity see black people as walking hyperbole.