This is an attack on rappers who claim to be more than they actually are, especially Ja Rule.
50 had a feud with Ja Rule that supposedly dates back to when Ja was robbed by an acquaintance of 50's. The feud has included at least two separate physical fights, landing 50 with 4 stitches and Ja with some missing jewelry.
Starting a feud with another rapper can be dangerous, but it can also lead to huge sales. 50's 1999 song "How To Rob" became a hit when some of the rappers he jokingly dissed took offense and responded. This got the song a lot of attention, but not all the good kind. 50 was shot 9 times in a drive-by after it became an underground hit. Since he was already marked for death, it was no big deal to start more trouble with Ja Rule.
This was the track that brought 50 into the mainstream. It's more radio-friendly than most of his material.
This was one of the songs that 50 recorded to generate buzz in the New York mix tape underground. This led to a record deal with Shady/Aftermath Records, which is run by Dr. Dre and Eminem. They did a great job promoting 50 and his first album, Get Rich Or Die Tryin' was a huge hit, selling more copies in one week than any rapper except Eminem.
According to 50, a "Wanksta" is "a gangsta that doesn't progress." He says the whole point of being a gangsta is making money. Wankstas try, but have nothing to show for it.
50 Cent appeared on the soundtrack two more times. Once, with his own "Places to Go" and once with a guest appearance on Eminem's "Love Me."
"Wanker" is a derogatory term in England, generally meaning someone who masturbates. 50 Cent is from America, so he can say it on the air.
This was one of the last songs produced by Jam Master Jay, who mentored 50 and helped get him his first record deal. Jay was murdered at his recording studio in 2002.
50's son Marquise, who was 6 at the time, is in the video.