Its a word used all over Argentina to call a person, similar to "hey". It has no meaning,it is slightly informal, you can use it at the beginning, in the middle, or in the end of any thing you say. Ernesto "Che" Guevara was a revolutionary leader who as any other Argentinian used the word "che". He was called "che" in foreign countries beacuse he used the word very often, its not that the word was created after him!
"che, estás ocupado?" "hey, are you busy?"