The grammar news is that Dr. Elaine Stotko, from the School of Education at Johns Hopkins University, and her student, Margaret Troyer, have discovered that school children in Baltimore are using the slang word yo as a gender-neutral singular pronoun. Dr. Stotko was teaching a master’s class at Johns Hopkins, and it came out during a discussion that several of the high school and middle school English teachers had noticed their students using yo as a pronoun. Often the students would be talking to another student, would point at the third person they were referring to, and would say something like “Yo threw a thumbtack at me.” This made teachers think they were using yo to mean “he or she” instead of yo as you would normally hear in phrases like “Yo momma.”
To test the theory, Stotko and Troyer showed kids a cartoon with a goofy-looking person, but the kids couldn’t tell whether the person was male or female. Then they asked the kids to write a slang caption for the cartoon. Some of the kids wrote, “Yo crazy,” instead of “He or she crazy,” or “They crazy.” Follow-up research showed that kids definitely intended yo to mean “he or she.” They used yo as a pronoun.
|—||Grammar Girl, “Yo as a Pronoun”|