It’s a job that is “poorly paid and menial” according to the Collins Dictionary and by the Oxford English Dictionary as an "unstimulating, low-paid job with few prospects, esp. one created by the expansion of the service sector", so no wonder McDonalds wants to change the definition of the word McJob. But how do you go about changing a dictionary definition if you don’t like it? Well, not by pressurising the lexicographers, if this quote from The Language Log is anything to go by: Sydney Landau, in his book, Dictionaries: the Art and Craft of Lexicography (Cambridge U Press, 2001) says that the lexicographer "cannot allow any special-interest group to determine what gets in his dictionary or how it is represented" (page 407). That would seem to discourage McDonald's from being too pushy with lexicographers, who have their own methods of determining meaning and who don't much cater to external pressures from industry.
So, how are dictionaries compiled and what do lexicographers do? The latest update to the OED has just come out, and some of their experts talk about the new words and how they collect them here:
http://www.oed.com/news/newwords.html
http://www.oed.com/news/revisions.html
Useful for:
ENA5 – Language Change