What started out as playground insults in primarily urban and inner city neighborhoods has evolved into an entire humor category known as yo mama jokes. Yo mama jokes are targeted at a challenger's mother because family insults are widely considered to be the most offensive in urban culture. While the confrontation may start out with personal insults and slurs, it may devolve quickly into a series of crude insults against each other's mothers: "Yo mama's so fat, she needs a map to find her butt." "Well, yo mama's so ugly, she put the boogie man out of business."
Yo mama jokes are urban variants on a tradition of verbal taunts and insults offered in the form of biting or sarcastic humor. The term "Yo mama" itself is short for "your mama," and is considered to be an example of urban slang known as Ebonics or Black English. Although the deliberate use of black slang may seem racist, many humor collections refer specifically to Yo mama jokes as a recognized category. Part of the humor behind yo mama jokes is the delivery of the punchline in an urban or Ebonic dialect.
Some other yo mama jokes target weight, intelligence or age: "Yo mama's so old, she sat in front of Jesus in the first grade!" "Oh yeah, yo mama's so stupid she took the Pepsi challenge and chose Jif!" "Yo mama's so fat she could be the eighth continent!" Few subjects are considered off-limits when crafting and hurling yo mama jokes, from poverty to personal hygiene. Other relatives may also become the target of insults and slurs, but crude or obscene remarks about one's mother tend to trigger the most emotional responses.
Yo mama jokes are not limited to urban or inner city areas of the United States. Many other cultures have their own form of insult humor, most of which is targeted at a rival's family members or community. "Yo mama" could easily be replaced by "Yo boyfriend" or "Yo family" or "Yo wife." The point of the exercise is to come up with a new insult that is so clever or cutting that the rival can no longer respond in kind.