Hey! FYI
yo
In tha English language, yo has become a common interjection that originated decades ago in a dialect spoken in the Philadelphia area. It is often interchangeable with the word "hey," as in "Yo, what's up?" or, "Yo! Wait for me!" While the word can also stand alone as a greeting, like the word "hey," it also has a wide range of meanings that depend on the tone, context, and situation in which it is used. Examples:
If someone is bothering another person, "Yo!" becomes the equivalent of saying "Hey! Stop it," or "Knock it off!"
If someone accidentially bumps into another person, the expression "Yo!" could be interpreted as "Hey! Watch it," or "What in the world!"
If someone did something that amazes or shocks another person, the word yo is like laughing or an expression of amazement.
In more recent times the word has spread into hip-hop or gangsta culture. A parody of such usage forms the basis for a comic exchange between the animated characters played by Robert DeNiro and Martin Scorsese (Shark Tale, 2004), which can be viewed here. The word's origin predates these recent uses, as is evidenced by the words of Rocky Balboa (played by Sylvester Stallone).
"Yo, Adrienne, it's me, Rocky..." Rocky Balboa (Rocky, 1976)
"Yo, Adrienne. We did it!" Rocky Balboa (Rocky II, 1979)
During the late 1990s / early 2000s, the word became very popular in rap songs, often chanted in the background between lines, tying in with the hip-hop and gangsta theme.
Korean Americans also use the term as an expression for disbelief; e.g., "Yoooooo...."
Although the exact uses are debatable, "yo" was first known to be used as a Middle English interjection. For the most part, 'yo' was used to call attention or express excitement, much like "hey". "Yo" was used frequently in certain Philadelphia dialects in the 1970s, but was more prevalently used as a greeting by infantry men in the second World War.