Bahaha! According to this AP article,
The squabble is over a fake letter sent out by Taco Bell Corp. asking 50 Cent to change his name for one day to 79 Cent, 89 Cent or 99 Cent to help publicize its value menu.
Michael Masnick of Techdirt describes Taco Bell’s letter as an open letter, which seems to lump this activity in with a nascent trend of for-profit corporations adopting “dot org” strategies and messages. Open letters strike me as a tool used by the “little guy” (consumers, activists, public interest organizations) to open up an assault on a more powerful entity; receiving any kind of response from the target is basically a victory. Here, Taco Bell has co-opted a strategy more often used to bring about a public good — instead successfully using it to bring about a private good (awareness and profits for itself). They inverted the typical power structure too — in this odd situation, a huge corporation used an open letter to pick on an individual rapper.

(Photo of 50 Cent Wheelie Bin by David Jones under a Creative Commons 2.0 Attribution-Noncommercial License.)
Extrapolations aside, this whole episode is plainly hilarious.