This type of humor harms its subject

The process of releasing, and thereby providing relief from, strong or repressed emotions.

http://youtu.be/wLgzuFvT2v8

Under this theory, hostile humor can serve as a positive psychological function...

Greek ideal, etymologically “to
say everything,” it's a practice of frank criticism that rejected hierarchy.

http://youtu.be/wLgzuFvT2v8?t=13m38s

Under this theory, humor derives from the triumph one feels in recognizing the infirmities or misfortunes of others...

The informal, common-sense explanations people give for particular social behaviors - are often very different from formal 'scientific' explanations of what actually happens. ...

IDENTITY THREAT -> DISPARAGEMENT HUMOR -> POSITIVE DISTINCTIVENESS -> AMUSEMENT

When there is a connection between humor and racist beliefs—where the jokes express racist beliefs- then one condition for this type of humor is met